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 EXHIBIT 10.1  

    EXHIBIT 10.1. Stock Exchange Agreement dated January 1, 2000, between Calendar Capital, Inc. and Entrenaut, Inc.

 STOCK EXCHANGE AGREEMENT  

    THIS STOCK EXCHANGE AGREEMENT (this "Agreement") is made and entered into on the dates set forth below, to be
effective as of January 1, 2000, by and between CALENDAR CAPITAL, INC., a Minnesota corporation ("CC"), and ENTRENAUT, INC., a
Minnesota corporation ("Entrenaut").

    The
persons listed in the shareholder list provided by Entrenaut to CC (the "Entrenaut Shareholder List") are all of the shareholders of Entrenaut. Such persons are referred to herein
as the "Acquired Company's Shareholders." Entrenaut is sometimes referred to herein as the "Acquired Company" because the transactions described below will result in the acquisition of all of the
issued and outstanding stock of Entrenaut by CC. CC, the Acquired Company, and the Acquired Company's Shareholders are referred to collectively herein as the "Parties" and sometimes individually as a
"Party."

    The
Acquired Company's Shareholders may agree to be bound by the terms of this Agreement that are applicable to them by (i) signing a signature page or (ii) signing any
other document or agreement that indicates an intention on the part of the signer to be bound by the terms of this Agreement and to approve the transactions provided for in this Agreement. Any
Acquired Company's Shareholder may also indicate his, her or its intention to be bound by this Agreement by taking the actions of an Acquired Company's Shareholder as provided for herein, even if the
Acquired Company Shareholder does not sign a signature page or undertaking to be bound by this Agreement.

 RECITALS  

    A.  On December 8, 1999, CC and Entrenaut signed a letter of intent (the "Letter of Intent").

    B.  The
Letter of Intent provides for CC (and its shareholders, as required) following the Closing (defined below) (a) to change the corporate name of CC to
Entrenaut, Inc., a Minnesota corporation, (b) to elect a new board of directors selected by Entrenaut, (c) to acquire all of the issued and outstanding stock of Entrenaut in
exchange for a number of shares of newly issued and restricted Series C Preferred Convertible Stock (the "Acquisition Stock") of CC that will be issued to the Acquired Company's Shareholders,
at the rate of two (2) shares of acquisition stock for each one (1) share of Entrenaut Common stock, (d) to obtain and to accept the resignation of all existing CC officers and
directors effective as of the Closing Date (defined below) (e) to complete any and all delinquent regulatory filings for CC (if any), and (f) to provide all requested due diligence
materials to Entrenaut, including a representation stating that there is no outstanding or pending litigation against CC, that all regulatory filings have been made as required by applicable law, that
CC is in good standing in various states and other matters reasonably required by the Acquired Company. The Acquisition Stock will be issued in exchange for all of the issued and outstanding stock of
the Acquired Company (the "Acquired Company's Stock"). After such exchange, the Acquired Company will be a wholly owned subsidiary of CC.

    C.  The
Letter of Intent provides for the Acquired Company's Shareholders to transfer to CC, in exchange for the Acquisition Stock, all of the Acquired Company's Stock.

    D.  The
Parties wish to enter into this Agreement to definitively provide for several of the transactions that are contemplated in the Letter of Intent. When executed
and delivered by the Parties as provided below, this Agreement will supersede and replace the Letter of Intent so far as the transactions provided for in this Agreement are concerned. Other provisions
of the Letter of Intent, if any, that are
not otherwise provided for in this Agreement, will survive execution of this Agreement by the Parties unless superseded by any other agreements of the Parties.

 AGREEMENT  

    THEREFORE, in consideration of the mutual covenants and conditions herein contained, and for other good and
valuable consideration, the sufficiency and receipt of which are hereby acknowledged, the Parties, intending to be legally bound, hereby agree as follows.

 ARTICLE I
 SHARE EXCHANGES  

    1.1  STOCK EXCHANGES.  CC hereby agrees to sell, convey, assign and transfer the Acquisition Stock to the
Acquired Company's Shareholders in exchange for their sale, conveyance, assignment and transfer to CC of the Acquired Company's Stock. The Acquired Company's Shareholders and the Acquired Company
hereby agree, jointly and severally, to sell, convey, assign and transfer, and/or to cause transfer to be made of, the Acquired Company's Stock to CC in exchange for sale, conveyance, assignment and
transfer to the Acquired Company's Shareholders of the Acquisition Stock. Unless the Acquired Company's Shareholders otherwise direct, the Acquisition Stock will be transferred to them in the same
proportions as the Acquired Company's Shareholders currently own the Acquired Company's Stock, as shown in the ENTRENAUT Shareholder List.

    1.2  CLOSING.  Consummation of the transactions described in this Agreement (the "Closing") will occur at
9:00 a.m. on or before March 31, 2000 (the "Closing Date") at the offices of Messerli & Kramer P.A. in Minneapolis, Minnesota or at such other location as is mutually agreeable to
the Parties.

    1.3  RESTRICTIONS ON TRANSFERABILITY OF THE ACQUISITION STOCK.  At the Closing, CC will convey to the
Acquired Company's Shareholders good, valid and marketable title to the Acquisition Stock, free and clear of any and all encumbrances, claims, liens, security interests, pledges or mortgages of any
kind. The Acquisition Stock will be newly issued stock. The Parties hereby agree that the Acquisition Stock, once acquired by the Acquired Company's Shareholders, will be subject to the restrictions
of SEC Rule 144. Unless and until the Acquisition Stock is registered under the Securities Act of 1933 or the Securities Exchange Act of 1934, or until restrictions under Rule 144 lapse
or would have lapsed, if Rule 144 in fact applied to the Acquisition Stock, no Acquired Company's Shareholder will be entitled to transfer all or any share of the Acquisition Stock to any other
person or party, unless the Acquired Company's Shareholder first provides CC with an acceptable opinion of counsel that the proposed transfer will not violate any applicable law, rule or regulation or
any provision of this Agreement. CC will be entitled to place a restrictive legend on all certificates evidencing ownership of the Acquisition Stock that provides notice of the provisions of this
paragraph and other applicable provisions of this Agreement.

    1.4  STOCK CONVEYED BY THE ACQUIRED COMPANY'S SHAREHOLDERS.  At the Closing the Acquired Company's
Shareholders will convey to CC good, valid and marketable title to the Acquired Company's Stock, free and clear of any and all encumbrances, claims, liens, security interests, pledges or mortgages of
any kind. The Acquired Company's Stock conveyed to CC will constitute all of the issued and outstanding stock of the Acquired Company. Following delivery to CC of the Acquired Company's Stock, the
Acquired Company will deliver a new stock certificate to CC that will replace the Acquired Company's Stock certificate delivered to CC as delivered above. The new certificate will be issued in the
name of CC.

 ARTICLE II
 DELIVERIES BY CC AT THE CLOSING  

    2.1  DELIVERIES BY CC.  In addition to the other items required to be delivered by CC at the Closing
under this Agreement, CC will deliver all of the following items to one or more of the Acquired Company's Shareholders:

    (a) the
Acquisition Stock to the Acquired Company's Shareholders, by delivery of certificates evidencing ownership of the Acquisition Stock by the Acquired Company's
Shareholders;

    (b) a
certified copy of CC's articles of incorporation, amended as necessary to authorize issuance of the Acquisition Stock, together with a certificate of CC's
Secretary, confirming that the Acquisition Stock has been duly issued as required in this Agreement;

    (c) a
current Certificate of Good Standing of CC, issued by the Secretary of State of the State of Minnesota;

    (d) corporate
records of CC consisting of at least the following: certified copies of CC's bylaws, complete minute books and a copy of CC's stock transfer ledger;

    (e) an
unaudited balance sheet of CC dated as of September 30, 1999, prepared by CC's accountants in accordance with generally accepted accounting principles
consistently applied, certified as accurate and as having been prepared in accordance with generally accepted accounting principles consistently applied by the person or firm who prepared the balance
sheet;

    (f)  a
stock transfer ledger of CC, stating the names of all CC shareholders, their addresses, their social security or federal tax ID numbers, the number of shares of
CC owned by each shareholder, the date of acquisition of the shares and information about all transfers of shares of CC that have been made since its original incorporation, certified as true,
correct, complete and accurate by the Secretary of CC or the person responsible for preparing and maintaining such stock transfer ledger;

    (g) certificates
of the Secretary and the Vice President or the President of CC verifying the accuracy and authenticity of all corporate records, other materials,
disclosures, exhibits to this Agreement and/or all other documents and information of CC delivered or provided by CC at the Closing, and confirming the accuracy on the Closing Date of all
representations and warranties of CC contained herein;

    (h) resignations
of all officers and members of the board of directors of CC, effective as of or prior to the Closing Date;

    (i)  certified
copies of resolutions of the board of directors of CC authorizing execution and delivery of this Agreement by CC and consummation by CC of all of the
transactions that are contemplated herein;

    (j)  a
legal opinion of CC's counsel, addressed to the Acquired Company and CC, in form that is mutually agreeable to the Parties and which includes confirmation that
CC is current in making all SEC and similar filings required by applicable law, and that CC is not in violation of any state or federal securities laws, and that, to the best of such counsel's
knowledge after inquiry of the officers of CC, there is no outstanding or pending litigation against CC;

    (k) copies
of all contracts, loan agreements, memoranda and other documents or instruments (in an amount of $5,000 or more) to which CC is a party or by which it is
bound or to which it or any of its assets is subject; and

    (l)  copies
of all SEC Forms 10-QSB and 10-KSB (and 8K, if any) filed by CC with the SEC, indicating that CC is current in making all required
SEC filings, and a copy of the SEC Form 14C filed by CC in connection with the transactions contemplated in this Agreement, together with all correspondence from the SEC relating to such
Form 14C and evidence that the Form 14C has been approved by the SEC.

    2.2  OTHER DOCUMENTS AND INSTRUMENTS.  CC will also deliver any and all such other documents and
instruments of conveyance, assignment and transfer, and such other items, as may be reasonably requested or necessary in order to vest good and marketable title to the Acquisition Stock in the
Acquired Company's Shareholders, on or prior to the date of the Closing. All instruments and other documents or instruments exchanged by the Parties will be in form as needed to effectuate the
transactions contemplated by this Agreement or to evidence the same, and will include any third party consents to the transactions contemplated herein that may be required by the provisions of any
contracts, agreements or obligations to which CC is a party or pursuant to which a change in the stock ownership of CC is deemed to constitute an assignment or transfer requiring such consent or
approval. These additional conveyances

and transfers will be made by CC with a view toward placing the Acquired Company's Shareholders, on or prior to the date of the Closing in actual possession and full and complete ownership of the
Acquisition Stock as provided herein.

 ARTICLE III
 DELIVERIES BY THE ACQUIRED COMPANY AND
 THE ACQUIRED COMPANY'S SHAREHOLDERS
 AT THE CLOSING  

    3.1  DELIVERIES BY THE ACQUIRED COMPANY'S SHAREHOLDERS.  In addition to all other items required to be
delivered by the Acquired Company and the Acquired Company's Shareholders at the Closing under this Agreement, at the Closing (or after, if indicated below) the Acquired Company and the Acquired
Company's Shareholders will deliver all of the following items to CC:

    (a) all
of the Acquired Company's Stock, by delivery to CC of one or more share certificates evidencing ownership of all of the Acquired Company's Stock, with each
certificated endorsed in blank by the Acquired Company's Shareholder who owns such certificate;

    (b) certified
copies of the Acquired Company's articles of incorporation, together with certificates of the Acquired Company's confirming that the Acquired Company's
Stock has been duly transferred on the books and records, and in the stock transfer ledgers of the Acquired Company, as required in this Agreement;

    (c) a
current Certificate of Good Standing of the Acquired Company, issued by the Secretary of State of the State of Minnesota;

    (d) corporate
records of the Acquired Company's Shareholders consisting of at least the following: certified copies of the Acquired Company's Shareholders' bylaws,
complete minute books and a copy of the Acquired Company's Shareholders' stock transfer ledger;

    (e) an
audited balance sheet of Entrenaut dated as of December 31, 1999, prepared by Entrenaut's accountants in accordance with generally accepted accounting
principles consistently applied, certified as accurate and as having been prepared in accordance with generally accepted accounting principles consistently applied by the person or firm who prepared
the balance sheet;

    (f)  a
stock transfer ledger of Entrenaut, stating the names of all Entrenaut shareholders, their addresses, their social security or federal tax ID numbers, the number
of shares of Entrenaut owned by each shareholder, the date of acquisition of the shares and information about all transfers of shares of Entrenaut that have been made since its original incorporation,
certified as true, correct, complete and accurate by the Secretary of Entrenaut or the person responsible for preparing and maintaining such stock transfer ledger;

    (g) a
correct statement of the number of issued and outstanding shares of stock of Entrenaut as of the Closing date;

    (h) copies
of resumes of all of the persons who will serve as directors and officers of CC after the Closing;

    (i)  certificates
of the Secretary and the Vice President or the President of the Acquired Company verifying the accuracy and authenticity of all corporate records,
other materials, disclosures or documents pertaining to the Acquired Company delivered or provided by the Acquired Company's Shareholders at the Closing, and confirming the accuracy on the Closing
Date of all representations and warranties of the Acquired Company's Shareholders and the Acquired Company as contained herein;

    (j)  certified
copies of resolutions of the board of directors of the Acquired Company authorizing execution and delivery of this Agreement by the Acquired Company and
consummation by the Acquired Company of all of the transactions that are contemplated herein;

    (k) evidence
reasonably satisfactory to CC that, as of or prior to the Closing Date, Entrenaut and Paul D. Crawford own all of the issued and outstanding stock of
Chefinabox, Inc., OfficeCause.com, Inc., and Istoleit.com, Inc., Minnesota corporations;

    (l)  a
legal opinion of Entrenaut's counsel, addressed to CC, in form that is mutually agreeable to the Parties and which includes confirmation that Entrenaut is not in
violation of any state or federal securities laws, and that, to the best of such counsel's knowledge after inquiry of the officers of Entrenaut, there is no outstanding or pending litigation against
Entrenaut; and

    (m) copies
of all contracts of $5,000 (U.S.) or more, loan agreements, memoranda and other documents or instruments to which the Acquired Company is a party or by which
it is bound or to which it or any of its assets is subject.

    3.2  OTHER DOCUMENTS AND INSTRUMENTS.  The Acquired Company and the Acquired Company's Shareholders will
also deliver to CC any and all such other documents and instruments of conveyance, assignment and transfer, and such other items, as may be reasonably requested or necessary in order to vest good and
marketable title to the Acquired Company's Stock in CC on or prior to the date of the Closing. All instruments and other documents or instruments exchanged by the Parties will be in form as needed to
effectuate the transactions contemplated by this Agreement or to evidence the same, and will include any third party consents to the transactions contemplated herein that may be required by the
provisions of any contracts, agreements or obligations to which the Acquired Company is a party or pursuant to which a change in the stock ownership of the Acquired Company is deemed to constitute an
assignment or transfer requiring such consent or approval. These additional conveyances and transfers will be made by the Acquired Company with a view toward placing CC on, or prior to, the date of
the Closing in actual possession and ownership of all of the Acquired Company's Stock as provided herein.

 ARTICLE IV
 REPRESENTATIONS AND WARRANTIES OF CC  

    4.1  REPRESENTATIONS AND WARRANTIES OF CC.  CC hereby represents and warrants to, and covenants with,
Entrenaut and the Acquired Company's Shareholders that the representations and warranties provided below are true, correct, accurate and complete in any and all respects as of the effective date of
this Agreement, and that the same will be true, correct, accurate and complete on and as of the date of the Closing (as though made then and as though the Closing were substituted for the date of this
Agreement throughout the following), except as may be set forth in the Disclosure Schedule attached hereto (the "CC Disclosure Schedule"). The CC Disclosure Schedule will be arranged in paragraphs and
subparagraphs that correspond to the designation of subparagraphs below.

    4.2  ORGANIZATION OF CC.  CC is a corporation that is duly organized, validly existing, and in good
standing in all material respects under the laws of the State of Minnesota.

    4.3  AUTHORIZATION OF TRANSACTION.  CC has full actual and legal corporate power and corporate authority
to execute and deliver this Agreement and to perform its obligations hereunder.

    4.4  ENFORCEABLE OBLIGATION.  This Agreement constitutes the valid and legally binding obligation of CC,
enforceable against CC in accordance with this Agreement's terms.

    4.5  NONCONTRAVENTION.  Neither the execution and the delivery of this Agreement, nor the consummation of
the transactions contemplated hereby by CC will (i) to CC's knowledge, violate any statute, law, regulation, rule, judgment, order, decree, stipulation, injunction, charge, or other restriction
of any government, governmental agency, or state or federal court to which CC or the Acquisition Stock are subject or any provision of the articles of incorporation or bylaws or similar governing
rules or documents of CC, (ii) conflict with, result in a breach of, constitute a default under, result in the acceleration of, create in any party the right to accelerate, terminate, modify or
cancel, or require any notice under any governmental rule, law or regulation of any state or federal court or under any contract, lease, sublease, license, sublicense, franchise, permit, indenture,
agreement or mortgage or instrument of indebtedness or under any other arrangement to which CC is a party or by which it or the Acquisition Stock are bound or to which it or any of the Acquisition
Stock is subject, (iii) nor result in the imposition of any lien,

encumbrance, claim or security interest in, to or affecting any of the Acquisition Stock. To its knowledge, CC does not need to give any notice to, make any filing with, or obtain any authorization,
consent, or approval of any state or federal government or governmental agency in order for the Parties to consummate the transactions contemplated by this Agreement, except those that will be
obtained or made prior to Closing or those which would fail to have a material adverse effect on the ability of CC to consummate the transactions contemplated by this Agreement.

    4.6  THE ACQUISITION STOCK.  As of the date of Closing, the Acquisition Stock will constitute, on an
as-converted basis, in the aggregate, not less than 90% of all of the issued and outstanding common stock of CC after the Closing, with the rights, privileges and preferences that are
described in CC's articles of incorporation. As of the date of Closing the Acquisition Stock will have been duly and validly issued and is and will be nonassessable. The Acquisition Stock will be
restricted stock, consistent with the provisions of this Agreement. Title to the Acquisition Stock will be in the name of the Acquired Company's Shareholders in the official records of CC and in the
records of CC's stock transfer agent, if any.

    4.7  LITIGATION.  CC is not subject to any unsatisfied judgment, order, decree, stipulation, injunction,
or charge nor is it a party or threatened to be made a party to any charge, complaint, action, suit, proceeding, hearing, or investigation of or in any court or quasi-judicial or administrative agency
of any federal, state or local jurisdiction or before any arbitrator that relates in any way, directly or indirectly, to the transactions contemplated in this Agreement. CC has no actual reason to
believe that any charge, complaint, action, suit, proceeding, hearing, or investigation will or may be brought or threatened against CC in connection with the transactions contemplated in this
Agreement.

    4.8  SEC AND BLUE SKY COMPLIANCE.  CC is in compliance with all requirements of all federal and state
securities laws applicable to CC.

    4.9  MATERIAL INFORMATION.  As of the Closing, no representation or warranty by CC, nor any statement or
certificate furnished or to be furnished to the Acquired Company's Shareholders pursuant hereto or in connection with the transactions contemplated hereby, nor any filing made by CC with the SEC or
any state securities regulatory entity or authority contains or will contain any untrue statement of a material fact, or omits or will omit to state any material fact necessary to make the
representation, warranty, statement or certificate not misleading. At or prior to the Closing CC will deliver to the Acquired Company's Shareholders a Disclosure Document (the "CC Disclosure
Document") in the form of a CC Proxy Statement that provides the Acquired Company's Shareholders with all material information concerning CC and the Acquisition Stock, as required by the Securities
and Exchange Commission, and CC and the Acquired Company's Shareholders will take all actions and steps that are necessary to cause the Acquired Company's Shareholders' acquisition of the Acquisition
Stock to be qualified under applicable rules and regulations of the Securities and Exchange Commission as a private placement of securities and to be similarly qualified under applicable provisions of
state laws. The Parties will cooperate with each other in signing documents and forms to be filed with federal and state regulatory agencies to accomplish the results contemplated in this paragraph.

    4.10  DOCUMENTATION.  Prior to the Closing CC will deliver to the Acquired Company's Shareholders,
materially correct, accurate and complete copies of all of the contracts in an amount of $5,000 or more, and agreements and documents that comprise or relate to CC or the Acquisition Stock in any way.
As to each such contract, agreement, or document (collectively, each "Contract"):

    (a) the
Contract is the legal, valid, binding, and enforceable obligation of the parties thereto as of the Closing Date, and is in full force and effect as of the
Closing Date;

    (b) to
the extent permitted by applicable law, after the Closing, each Contract will continue to be legal, valid, binding, enforceable, and in full force and effect on
identical terms following the Closing;

    (c) no
party to the Contract is in breach or default, and no event has occurred which, with notice or lapse of time, would constitute a breach or default or permit
termination, modification, or acceleration of the Contract;

 

    (d) no
party to the Contract has repudiated, breached or anticipatorily breached any provision thereof, nor is there any reason to think that any such is likely to
occur or may occur in the future;

    (e) there
are no disputes, oral agreements, or forbearance programs in effect as to the Contract; and

    (f)  CC
has not assigned, transferred, conveyed, mortgaged, deeded in trust, or encumbered any interest in the Contract.

    4.11  LEGAL COMPLIANCE.  

    (a) CC
has complied in all material respects with all laws (including rules and regulations thereunder) of federal, state and local governments (and all agencies
thereof), and no charge, complaint, action, suit, proceeding, hearing, investigation, claim, demand, or notice has been filed or commenced against any of CC alleging any failure to comply with any
such law or regulation.

    (b) CC
has complied in all material respects with all applicable laws (including rules and regulations thereunder) relating to the employment of labor, employee civil
rights, and equal employment opportunities.

    4.12  RECEIPT OF DISCLOSURE SCHEDULE.  Prior to Closing, CC received and reviewed a copy of the Acquired
Company's Disclosure Schedule described in Section 5.9 below, had discussions with representatives of the Acquired Company and the Acquired Company's Shareholders, and received from such
representatives all such additional documents and information as CC requested.

    4.13  RESTRICTED STOCK.  CC understands that the Acquired Company's Stock will not be registered with the
Securities and Exchange Commission, and that transferability of the Acquired Company's Stock will be subject to the provisions and restrictions of state and federal securities laws.

    4.14  REGISTRATION REPRESENTATIONS.  CC is the sole party in interest agreeing to purchase the Acquired
Company's Stock by entering into this Agreement. CC is acquiring the Acquired Company's Stock for investment purposes only and not with a view to the resale or other distribution thereof, in whole or
in part. As stated in the previous paragraph, CC is aware that as of the date of Closing the Acquired Company's Stock has not been and will not be registered under the 1933 Act.

    4.15  THIRD PARTY CONSENTS.  All third parties whose consent to the transactions contemplated in this
Agreement are listed in the Disclosure Schedule. The Disclosure Schedule also indicates the contract, agreement, permit or other relationship to the third party that gives rise to the need for the
third party's consent.

    4.16  DUE DILIGENCE PERIOD.  During the time period from the effective date of this Agreement until the
Closing date (the "Due Diligence Period"), CC will be entitled to investigate the Acquired Company, review its files, visit the Acquired Company's business premises and to talk with officers and
employees of the Acquired Company and to meet with any and all other third parties, public and private, and to perform such other due diligence reviews and investigations pertaining to the
transactions contemplated in this Agreement as CC determines is necessary or proper.

    4.17  FINANCIAL STATEMENTS.  CC has provided to Entrenaut balance sheets and income statements of CC (the
"CC Financial Statements"). The CC Financial Statements have been prepared in accordance with generally accepted accounting principles consistently applied, and are true and accurate. The CC Financial
Statements provided in connection with transactions contemplated in this Agreement are true, correct and accurate in all respects. Since the date of the CC Financial Statements, there has been no
change in the financial condition of CC. CC has no liabilities (including without limitation tax
liabilities), commitments or obligations, contingent or otherwise, that are not shown on the CC Financial Statements.

    4.18  CAPITALIZATION.  All information relating to the authorized and outstanding shares of stock of CC
that has been provided by CC in connection with transactions contemplated in this Agreement is true, correct and accurate in all respects.

    4.19  PENDING OR THREATENED LITIGATION.  There is no pending or, to the best of CC's knowledge,
threatened litigation against CC by any party or person.

 ARTICLE V
 REPRESENTATIONS, WARRANTIES AND COVENANTS OF
 THE ACQUIRED COMPANY  

    The Acquired Company represents and warrants to, and covenants with, CC, that the representations and warranties provided below are true, correct, accurate and
complete in all respects as of the effective date of this Agreement, and that the same will be true, correct, accurate and complete on and as of the date of the Closing (as though made then and as
though the Closing were substituted for the date of this Agreement throughout the following), except as may be set forth in the Disclosure Schedule attached hereto (the "Acquired Company's Disclosure
Schedule"). The Acquired Company's Disclosure Schedule will be arranged in paragraphs and subparagraphs that correspond to the designation of subparagraphs below.

    5.1  ORGANIZATION OF THE ACQUIRED COMPANY.  The Acquired Company is a corporation that is duly organized,
validly existing, and in good standing in all material respects under the laws of the State of Minnesota. The description of the Acquired Company's Stock that is contained in the Entrenaut Shareholder
List is a true, correct, complete and accurate description. The Acquired Company's Shareholders own 100% of all of the issued and outstanding stock of the Acquired Company's Stock. A true, accurate
and complete statement as to outstanding Warrants and options to acquire the Acquired Company's Stock will be provided.

    5.2  AUTHORIZATION OF TRANSACTION.  The Acquired Company has full actual and legal corporate power and
corporate authority to execute and deliver this Agreement and to perform its obligations hereunder.

    5.3  ENFORCEABLE OBLIGATION.  This Agreement constitutes the valid and legally binding obligation of the
Acquired Company, enforceable against it in accordance with this Agreement's terms.

    5.4  NONCONTRAVENTION.  Neither the execution and delivery of this Agreement by the Acquired Company, nor
the consummation by any of them of the transactions contemplated hereby, will (i) to Entrenaut's knowledge, violate any statute, law, regulation, rule, judgment, order, decree, stipulation,
injunction, charge, or other restriction of any government, governmental agency, or court to which the Acquired Company or the Acquired Company's Shareholders or the Acquired Company's Stock are
subject, or any provision of the articles of incorporation or bylaws or similar governing rules or documents of the Acquired Company, (ii) conflict with, result in a breach of, constitute a
default under, result in the acceleration of, create in any party the right to accelerate, terminate, modify or cancel, or require any notice under any governmental rule, law or regulation or under
any contract, lease, sublease, license, sublicense, franchise, permit, indenture, agreement or mortgage or instrument of indebtedness or under any other arrangement to which the Acquired Company or
the Acquired Company's Shareholders is a party or by which any of them is bound or to which any of them is subject, (iii) nor result in the imposition of any lien, encumbrance, claim or
security interest in, to or affecting any assets of the Acquired Company or the Acquired Company's Stock. No Acquired Company or Acquired Company Shareholder needs to give any notice to, make any
filing with, or obtain any authorization,
consent, or approval of any government or governmental agency in order for the Parties to consummate the transactions contemplated by this Agreement.

    5.5  DOCUMENTATION.  Prior to the Closing, the Acquired Company will deliver to CC true, correct,
accurate and complete copies of all of the contracts, agreements and documents that comprise or relate to the Acquired Company or the Acquired Company's Stock in any way. As to each such contract,
agreement, or document (collectively, each "Contract"):

    (a) the
Contract is the legal, valid, binding, and enforceable obligation of the parties thereto as of the Closing Date, and is in full force and effect as of the
Closing Date;

    (b) to
the extent permitted by applicable law, after the Closing, each Contract will continue to be legal, valid, binding, enforceable, and in full force and effect on
identical terms following the Closing;

    (c) no
party to the Contract is in breach or default, and no event has occurred which, with notice or lapse of time, would constitute a breach or default or permit
termination, modification, or acceleration of the Contract;

    (d) no
party to the Contract has repudiated, breached or anticipatorily breached any provision thereof, nor is there any reason to think that any such is likely to
occur or may occur in the future;

    (e) there
are no disputes, oral agreements, or forbearance programs in effect as to the Contract; and

    (f)  the
Acquired Company has not assigned, transferred, conveyed, mortgaged, deeded in trust, or encumbered any interest in the Contract.

    5.6  LITIGATION.  The Acquired Company is not subject to any unsatisfied judgment, order, decree,
stipulation, injunction, or charge, nor is the Acquired Company a party or threatened to be made a party to any charge, complaint, action, suit, proceeding, hearing, or investigation of or in any
court or quasi-judicial or administrative agency of any federal, state or local jurisdiction or before any arbitrator that relates in any way, directly or indirectly, to the transactions contemplated
in this Agreement. The Acquired Company has no reason to believe that any charge, complaint, action, suit, proceeding, hearing, or investigation will or may be brought or threatened against the
Acquired Company in connection with any of the transactions contemplated in this Agreement.

    5.7  LEGAL COMPLIANCE.  

    (a) The
Acquired Company has complied with all laws (including rules and regulations thereunder) of federal, state and local governments (and all agencies thereof), and
no charge, complaint, action, suit, proceeding, hearing, investigation, claim, demand, or notice has been filed or commenced against the Acquired Company alleging any failure to comply with any such
law or regulation.

    (b) The
Acquired Company has complied in all material respects with all applicable laws (including rules and regulations thereunder) relating to the employment of
labor, employee civil rights, and equal employment opportunities.

    5.8  MATERIAL INFORMATION.  As of the Closing, no representation or warranty made by the Acquired
Company, nor any statement or certificate furnished or to be furnished to any person or Party pursuant hereto or in connection with the transactions contemplated hereby, contains or will contain any
untrue statement of a material fact, or omits or will omit to state any material fact necessary to make the representation, warranty, statement or certificate not misleading. At or prior to the
Closing the Acquired Company will deliver to CC a Disclosure Document (the "Acquired Company's Disclosure Document") that provides CC with all material information concerning the Acquired
Company. The Parties will cooperate with each other in signing documents and forms to be filed with federal and state regulatory agencies to accomplish the results contemplated in this paragraph.

    5.9  RECEIPT OF DISCLOSURE SCHEDULE.  Prior to making the decision to acquire the Acquisition Stock as
provided herein, the Acquired Company and the Acquired Company's Shareholders received and reviewed a copy of the Disclosure Schedule described in Section 4.9, had discussions with
representatives of CC and received from such representatives such additional documents and information as the Acquired Company's Shareholder requested.

    Each
of the Acquired Company's Shareholders acknowledges that he or she is sophisticated and experienced in matters relating to CC and its planned business activities as described in
the Disclosure Schedule.

    5.10  RESTRICTED STOCK.  Each of the Acquired Company's Shareholders understands that the Acquisition
Stock will be restricted stock, not registered with the Securities and Exchange Commission. Unless and until the Acquisition Stock is registered under the Securities Exchange Act of 1934, no Acquired
Company's Shareholder will be entitled to transfer all or any share of the Acquisition Stock

unless the Acquired Company's Shareholder first provides CC with an acceptable opinion of counsel that the proposed transfer will not violate any applicable law, rule or regulation or any provision of
this Agreement. CC will be entitled to place a restrictive legend on all certificates evidencing ownership of the Acquisition Stock that provides notice of the provisions of this paragraph and other
applicable provisions of this Agreement. Unless otherwise provided in this Agreement, each of the Acquired Company's Shareholders will be prohibited from trading the Acquisition Stock for a period of
two years after the date of the Closing.

    5.11  REGISTRATION REPRESENTATIONS.  Each of the Acquired Company's Shareholders is the sole party in
interest agreeing to purchase the Acquisition Stock by entering into this Agreement. The Acquired Company's Shareholders are acquiring the Acquisition Stock for the Acquired Company's Shareholders'
own account, for investment purposes only and not with a view to the resale or other distribution thereof, in whole or in part. As stated above, the Acquired Company's Shareholders is aware that as of
the date of Closing the Acquisition Stock has not been and will not be registered under the 1933 Act and that CC provides no assurance that the Acquisition Stock will ever be registered under such
act. Each of the Acquired Company's Shareholders is willing and able and agrees to bear the economic risk of investment in the Acquisition Stock for an indefinite period of time, and each is capable
of bearing that risk. Each of the Acquired Company's Shareholders is knowledgeable with respect to the financial, tax and business aspects of ownership of the Acquisition Stock and of the business
operations conducted by CC, or the Acquired Company has been represented by a person with such knowledge and expertise in connection with acquisition of the Acquisition Stock.

    5.12  THIRD PARTY CONSENTS.  All third parties, if any, whose consent to the transactions contemplated in
this Agreement are listed in the Disclosure Schedule. The Disclosure Schedule also indicates the contract, agreement, permit or other relationship to the third party that gives rise to the need for
the third party's consent.

    5.13  DUE DILIGENCE PERIOD.  During the time period from the effective date of this Agreement until the
Closing date (the "Due Diligence Period"), the Acquired Company's Shareholders will be entitled to investigate CC, review its files, to visit CC's business premises and to talk with officers and
employees of CC and to meet with any and all other third parties, public and private, and to perform such other due diligence reviews and investigations pertaining to the transactions contemplated in
this Agreement as any Acquired Company's Shareholder determines is necessary or proper. The Acquired Company's Shareholders have received the financial statements of CC dated September 30,
1999.

    5.14  FINANCIAL STATEMENTS.  Entrenaut has provided to CC balance sheets and income statements of
Entrenaut (the "Entrenaut Financial Statements"). The Entrenaut Financial Statements have been prepared in accordance with generally accepted accounting principles consistently applied, and are true
and accurate. The Entrenaut Financial Statements provided in connection with transactions contemplated in this Agreement are true, correct and accurate in all respects. Since the date of the Entrenaut
Financial Statements, there has been no change in the financial condition of Entrenaut. ENTRENAUT has no liabilities, commitments or obligations, contingent or otherwise, that are not shown on the
ENTRENAUT Financial Statements.

 ARTICLE VI
 CONDITIONS PRECEDENT  

    6.1  CONDITIONS PRECEDENT TO THE OBLIGATIONS OF CC.  The following are conditions precedent to the
obligation of CC to sell and convey the Acquisition Stock to the Acquired Company's Shareholders and to receive an assignment of the Acquired Company's Stock at the Closing. Any condition listed below
may be waived by CC at or prior to the Closing Date.

    (a) Delivery
to CC of all information and materials required to be delivered under any provision of this Agreement;

    (b) Receipt
of all necessary third party consents;

    (c) Performance
by each Acquired Company Shareholder of all of his or her or its obligations under this Agreement that are required to be performed prior to Closing;

    (d) True
and correct representations and warranties by the Acquired Company and the Acquired Company's Shareholders in connection with this Agreement; and

    (e) Discovery
of no materially adverse information at or prior to the Closing concerning the Acquired Company.

    6.2  CONDITIONS PRECEDENT TO THE OBLIGATIONS OF THE ACQUIRED COMPANY'S SHAREHOLDERS.  The following are
conditions precedent to the obligations of Acquired Company's Shareholders to sell and transfer the Acquired Company Stock to CC, and to acquire the Acquisition Stock from CC, at the Closing. Any
condition listed below may be waived by the Acquired Company's Shareholders at or prior to the Closing.

    (a) Delivery
to the Acquired Company's Shareholders of all information and materials required to be delivered by CC under any provision of this Agreement;

    (b) Receipt
of all necessary third party consents;

    (c) Performance
by CC of all of its obligations under this Agreement that are required to be performed prior to Closing;

    (d) Receipt
of evidence of satisfactory completion of the transactions involving the Acquired Company Shareholders as described herein; and

    (e) Discovery
of no materially adverse information at or prior to the Closing concerning CC.

    6.3  SURVIVAL OF REPRESENTATIONS AND WARRANTIES.  The representations and warranties of the Parties
contained in this Agreement will survive the Closing and will continue to be the obligations of the Parties for a period of two years after the date of the Closing.

 ARTICLE VII
 GENERAL PROVISIONS  

    7.1  COSTS AND FEES.  If any Party breaches any term of this Agreement, the breaching Party agrees to pay
the non-breaching Party all reasonable attorneys' fees, expert witness fees, investigation costs, costs of tests and analysis, travel and accommodation expenses, deposition and trial
transcript costs, court costs and other costs and expenses incurred by the non-breaching Party in enforcing this Agreement or preparing for legal or other proceedings, at the trial or
appellate level, whether or not such proceedings are instituted. If any legal or other proceedings are instituted, the Party prevailing in any such proceeding will be paid all of the aforementioned
costs, expenses and fees by the other Party, and if any judgment is secured by such prevailing Party, all such costs, expenses, and fees will be included in such judgment, attorneys' fees to be set by
the court and not by the jury. References in this paragraph to "legal proceedings" refer to litigation as well as arbitration proceedings and any other similar or related proceedings.

    7.2  WAIVER.  No delay by a Party in exercising any right or remedy will constitute a waiver of a Party's
rights under this Agreement, and no waiver by any Party of the breach of any covenant of this Agreement by the other will be construed as a waiver of any preceding or succeeding breach of the same or
any other covenant or condition of this Agreement.

    7.3  INDEMNIFICATION.  Each Party (the "Indemnifying Party") will protect, indemnify and hold harmless
the other Party and its directors, officers, employees, agents, affiliates and representatives (each an "Indemnified Party") against any and all costs, expenses, damages (whether such damages are
general, special, consequential, limited, direct or indirect or incidental), liabilities or losses, including attorneys' fees, caused by, for or on account of the Indemnifying Party's negligence,
gross negligence or willful misconduct or failure to perform its obligations under this Agreement or the negligence, gross negligence or willful misconduct of the Indemnifying Party's directors,
officers, employees, agents affiliates or representatives.

    (a) If
an Indemnified Party intends to seek indemnification under this paragraph from any Indemnifying Party with respect to any action or claim, the Indemnified Party
will give the Indemnifying Party notice of such claim or action upon the receipt of actual knowledge or information by the Indemnified Party of any possible claim or of the commencement of such claim
or action, which period will in no event be later than the earlier of (i) fifteen business days prior to the last day of responding to such claim or action or (ii) one half of the period
allowed for responding to such claim or action or, if no time period for responding exists, as soon as reasonably possible. The Indemnifying Party will have no liability under this paragraph for any
claim or action for which such notice is not provided, unless the failure to give such notice does not prejudice the Indemnifying Party.

    (b) The
Indemnifying Party will have the right to assume the defense of any such claim or action, at its sole cost and expense, with counsel designated by the
Indemnifying Party and reasonably satisfactory to the Indemnified Party: provided, however, that if the defendants in any such action include both the Indemnified Party and the Indemnifying Party, and
the Indemnified Party will have reasonably concluded that there may be legal defenses available to it which are different from or additional to those available to the Indemnifying party, the
Indemnified Party will have the right to select separate counsel, at the Indemnifying Party's expense, to assert such legal defenses and to otherwise participate in the defense of such action on
behalf of such Indemnified Party.

    (c) Should
any Indemnified Party be entitled to indemnification under this Section as a result of a claim by a third party, and should the Indemnifying Party fail to
assume the defense of such claim or action, the Indemnified Party may, at the expense of the Indemnifying Party, contest or, (with the prior consent of the Indemnifying Party, which consent will not
be unreasonably withheld) settle such claim or action. Except to the extent expressly provided herein, no Indemnified Party will settle any claim or action with respect to which it has sought or
intends to seek indemnification pursuant to this Section without the prior written consent of the Indemnifying Party, which consent will not be unreasonably withheld or delayed.

    (d) If
an Indemnifying Party is obligated to indemnify and hold any Indemnified Party harmless under this Agreement, the amount owing to the Indemnified Party will be
the amount of such Indemnified Party's actual out-of-pocket loss, net of any insurance or other recovery.

    (e) The
duty to indemnify under this Agreement will continue in full force and effect for a period of two years with respect to any loss, liability, damage or other
expense based on facts or conditions which occurred prior to such termination.

    7.4  NOTICES.  No notice, consent, approval or other communication provided for herein or given in
connection herewith will be validly given, made, delivered or served unless it is in writing and delivered personally, sent by overnight courier, or sent by registered or certified United States mail,
postage prepaid, with return receipt requested, to the addresses for each Party set forth below. Any Party hereto may from time to time change its address by notice to the other Parties given in the
manner provided herein. Notices, consents, approvals, and communications by mail will be deemed delivered upon the earlier of forty-eight (48) hours after deposit in the United States mail in
the manner provided above or upon delivery to the respective addresses set forth above if delivered personally or sent by overnight courier. Addresses of the Parties are the following:

	To CC:	 	Calendar Capital, Inc.
	 	 	65 Main Street N.E., Suite 136
	 	 	Minneapolis, Minnesota 55414
	 	 	Telephone: 612-676-1436
	 

To the Acquired Company and the Acquired Company's Shareholders:
	 

 	 
 	 

Entrenaut, Inc.
	 	 	43 Main Street SE, Suite 200
	 	 	Minneapolis, Minnesota 55414
	 	 	Telephone: 612-362-8411

    7.5  INTERPRETATION AND TIME.  The captions of the paragraphs of this Agreement are for convenience only
and will not govern or influence the interpretation hereof. This Agreement is the result of negotiations between the Parties and, accordingly, will not be construed for or against any Party regardless
of which Party drafted this Agreement or any portion thereof. Time is of the essence under this Agreement.

    7.6  SUCCESSORS AND ASSIGNS.  All of the provisions hereof will inure to the benefit of and be binding
upon the successors and assigns of the Parties.

    7.7  NO PARTNERSHIP.  This Agreement is not intended to, and nothing contained in this Agreement will,
create any partnership, joint venture or other similar arrangement between the Parties.

    7.8  FURTHER DOCUMENTS.  Each of the Parties will execute and deliver all such other and additional
documents and perform all such acts, in addition to execution and delivery of this Agreement and performance of the Party's obligations hereunder, as are reasonably required from time to time in order
to carry out the purposes, matters and transactions that are contemplated in this Agreement.

    7.9  ORATION OF EXHIBITS.  All exhibits attached to this Agreement are by this reference incorporated
herein.

    7.10  GOVERNING LAW.  This Agreement will be governed by the laws of the State of Minnesota, without
giving effect to the conflict of law provisions or principles of the State of Minnesota.

    7.11  DATE OF PERFORMANCE.  If the date of performance of any obligation or the last day of any time
period provided for herein should fall on a Saturday, Sunday or legal holiday, then said obligation will be due and owing, and said time period will expire, on the first day thereafter which is not a
Saturday, Sunday or legal holiday. Except as may otherwise be set forth herein, any performance provided for herein will be timely made if completed no later than 5:00 p.m., Minneapolis,
Minnesota time, on the day of performance.

    7.12  COUNTERPARTS.  This Agreement may be executed in any number of counterparts. This Agreement may be
signed by original signatures or by fax signatures. Any set of counterparts of this Agreement, whether faxed or originals or both, showing signatures by all Parties, taken together, will constitute a
single copy of this Agreement.

    7.13  RESOLUTION OF DISPUTES.  In the event of any dispute between the Parties as to their rights and
obligations under this Agreement, including, but not limited to, any question as to whether or not a Party has performed its obligations fully or remedied an alleged breach, and any and all other
disputes arising under this Agreement, will be resolved as follows.

    (a) The
Parties will submit their dispute to at least four (4) hours of mediation in accordance with the mediation procedures of American Arbitration Association
("AAA").

    (b) In
the event the dispute does not then settle within 15 calendar days after the first mediation session, the Parties agree to submit the dispute to binding
arbitration in accordance with the arbitration procedures of the AAA except as modified in this Agreement. The arbitration hearing will be conducted no later than 45 calendar days after the first
mediation session.

    (c) The
arbitrator or arbitrators conducting the arbitration hearing will render the arbitration decision in writing, which writing will explain the reasoning and bases
for the decision.

    (d) The
Parties agree to share equally the costs of mediation. However, if the dispute is settled through arbitration, the prevailing Party will be entitled to recover
all costs incurred, including reasonable attorneys' fees, to enforce its rights hereunder, in addition to any damages recovered, as provided in "Costs and Fees" above.

    7.14  SEVERABILITY.  If any term or provision of this Agreement will, to any extent, be determined by a
court of competent jurisdiction to be invalid or unenforceable, the remainder of this Agreement will not be affected thereby, and each term and provision of this Agreement will be valid and be
enforceable to the fullest extent permitted by law.

    7.15  ASSIGNMENT.  No Party will assign this Agreement, nor any interest arising herein, without the
written consent of the other Parties.

    7.16  RECITALS.  The recitals set forth above are a part of this Agreement.

    7.17  JURISDICTION AND VENUE.  Venue for and jurisdiction over any legal proceedings available to the
Parties hereunder will lie in the appropriate courts of the State of Minnesota, located in Minneapolis, Minnesota.

    IN WITNESS WHEREOF, the Parties hereto have hereunder affixed their signatures on the dates set forth below to be effective as of the
date first set forth above.

	 	CALENDAR CAPITAL, INC.,

a Minnesota corporation,
	 

Date: January 1, 2000	 

By:	 

/s/ PAUL D. CRAWFORD   
 Paul D. Crawford,
Chief Executive Officer
	 
 	 
ENTRENAUT, INC.,

a Minnesota corporation,
	 

Date: January 1, 2000	 

By:	 

/s/ WAYNE ATKINS   
 Wayne Atkins,
President

QuickLinks

EXHIBIT 10.1

STOCK EXCHANGE AGREEMENT

RECITALS

AGREEMENT

ARTICLE I SHARE EXCHANGES

ARTICLE II DELIVERIES BY CC AT THE CLOSING

ARTICLE III DELIVERIES BY THE ACQUIRED COMPANY AND THE ACQUIRED COMPANY'S SHAREHOLDERS AT THE CLOSING

ARTICLE IV REPRESENTATIONS AND WARRANTIES OF CC

ARTICLE V REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE ACQUIRED COMPANY

ARTICLE VI CONDITIONS PRECEDENT

ARTICLE VII GENERAL PROVISIONS<PAGE>

                                                                 Exhibit 10.1

                          CUBIST PHARMACEUTICALS, INC.

                          REGISTRATION RIGHTS AGREEMENT

         This REGISTRATION RIGHTS AGREEMENT (this "AGREEMENT") is made as of
January 27, 2000 by and among (i) Cubist Pharmaceuticals, Inc., a Delaware
corporation (the "COMPANY"), (ii) each person listed on EXHIBIT A attached
hereto (collectively, the "INITIAL INVESTORS" and each individually, an "INITIAL
INVESTOR"), and (iii) each person or entity that subsequently becomes a party to
this Agreement pursuant to, and in accordance with, the provisions of Section 12
hereof (collectively, the "INVESTOR PERMITTED TRANSFEREES" and each individually
an "INVESTOR PERMITTED TRANSFEREE").

         WHEREAS, the Company has agreed to issue and sell to the Initial
Investors, and the Initial Investors have agreed to purchase from the Company,
2,200,000 shares (the "PURCHASED SHARES") of the Company's common stock, $.001
par value per share (the "COMMON STOCK"), all upon the terms and conditions set
forth in that certain Stock Purchase Agreement, dated of even date herewith,
between the Company and the Initial Investors (the "STOCK PURCHASE AGREEMENT");
and

         WHEREAS, the terms of the Stock Purchase Agreement provide that it
shall be a condition precedent to the closing of the transactions thereunder,
for the Company and the Initial Investors to execute and deliver this Agreement.

         NOW, THEREFORE, in consideration of the premises and mutual covenants
contained herein, the parties hereto hereby agree as follows:

         1. DEFINITIONS. The following terms shall have the meanings provided
therefor below or elsewhere in this Agreement as described below:

         "BOARD" shall mean the board of directors of the Company.

         "CLOSING" shall have the meaning ascribed to such term in the Stock
Purchase Agreement.

         "EXCHANGE ACT" shall mean the Securities Exchange Act of 1934, as
amended, and all of the rules and regulations promulgated thereunder.

         "INVESTORS" shall mean, collectively, the Initial Investors and the
Investor Permitted Transferees; PROVIDED, HOWEVER, that the term "INVESTORS"
shall not include any of the Initial Investors or any of the Investor Permitted
Transferees that ceases to own or hold any Purchased Shares.

         "MAJORITY HOLDERS" shall mean, at the relevant time of reference
thereto, those Investors holding and/or having the right to acquire, as the case
may be, more than fifty percent (50%) of the Registrable Shares held by all of
the Investors.

         "QUALIFYING HOLDER" shall have the meaning ascribed thereto in Section
12 hereof.

         "REGISTRABLE SHARES" shall mean the Purchased Shares, PROVIDED,
HOWEVER, such term shall not, after the Mandatory Registration Termination Date,
include any of the Purchased Shares that become or have become eligible for
resale pursuant to Rule 144 or pursuant to Regulation S.

         "RULE 144" shall mean Rule 144 promulgated under the Securities Act and
any successor or substitute rule, law or provision.

         "SEC" shall mean the Securities and Exchange Commission.

         "SECURITIES ACT" shall mean the Securities Act of 1933, as amended, and
all of the rules and regulations promulgated thereunder.

         2. EFFECTIVENESS; TERMINATION. This Agreement shall become effective
and legally binding only if the Closing occurs. This Agreement shall terminate
and be of no further force or effect, automatically and

<PAGE>

without any action being required of any party hereto, upon the termination of
the Stock Purchase Agreement pursuant to Section 7 thereof.

         3. MANDATORY REGISTRATION.

         (a) Within ten (10) business days after the Closing, the Company will
prepare and file with the SEC a registration statement on Form S-3 for the
purpose of registering under the Securities Act all of the Registrable Shares
for resale by, and for the account of, the Investors as selling stockholders
thereunder (the "REGISTRATION STATEMENT"). The Registration Statement shall
permit the Investors to offer and sell, on a delayed or continuous basis
pursuant to Rule 415 under the Securities Act, any or all of the Registrable
Shares. The Company agrees to use reasonable efforts to cause the Registration
Statement to become effective as soon as practicable. The Company shall be
required to keep the Registration Statement effective until such date that is
the earlier of (i) the date when all of the Registrable Shares registered
thereunder shall have been sold or (ii) the second anniversary of the Closing,
subject to extension as set forth below (such date is referred to herein as the
"MANDATORY REGISTRATION TERMINATION DATE"). Thereafter, the Company shall be
entitled to withdraw the Registration Statement and the Investors shall have no
further right to offer or sell any of the Registrable Shares pursuant to the
Registration Statement (or any prospectus relating thereto). In the event the
right of the selling Investors to use the Registration Statement (and the
prospectus relating thereto) is delayed or suspended pursuant to Sections 5(c)
or 11 hereof, the Company shall be required to extend the Mandatory Registration
Termination Date beyond the second anniversary of the Closing by the same number
of days as such delay or Suspension Period (as defined in Section 11 hereof).

         (b) The offer and sale of the Registrable Shares pursuant to the
Registration Statement shall not be underwritten.

         4. "PIGGYBACK" REGISTRATION RIGHTS.

         (a) If, at any time after the Mandatory Registration Termination Date,
the Company proposes to register any of its Common Stock under the Securities
Act, whether as a result of a primary or secondary offering of Common Stock or
pursuant to registration rights granted to holders of other securities of the
Company (but excluding in all cases any registrations to be effected on Forms
S-4 or S-8 or other applicable successor Forms), the Company shall, each such
time, give to the Investors holding Registrable Shares written notice of its
intent to do so. Upon the written request of any such Investor given within 20
days after the giving of any such notice by the Company, the Company shall use
reasonable efforts to cause to be included in such registration the Registrable
Shares of such selling Investor, to the extent requested to be registered;
PROVIDED that (i) the number of Registrable Shares proposed to be sold by such
selling Investor is equal to at least seventy-five percent (75%) of the total
number of Registrable Shares then held by such participating selling Investor,
(ii) such selling Investor agrees to sell those of its Registrable Shares to be
included in such registration in the same manner and on the same terms and
conditions as the other shares of Common Stock which the Company proposes to
register, and (iii) if the registration is to include shares of Common Stock to
be sold for the account of the Company or any party exercising demand
registration rights pursuant to any other agreement with the Company, the
proposed managing underwriter does not advise the Company that in its opinion
the inclusion of such selling Investor's Registrable Shares (without any
reduction in the number of shares to be sold for the account of the Company or
such party exercising demand registration rights) is likely to affect materially
and adversely the success of the offering or the price that would be received
for any shares of Common Stock offered, in which case the rights of such selling
Investor shall be as provided in Section 4(b) hereof.

         (b) If a registration pursuant to Section 4(a) hereof involves an
underwritten offering and the managing underwriter shall advise the Company in
writing that, in its opinion, the number of shares of Common Stock requested by
the Investors to be included in such registration is likely to affect materially
and adversely the success of the offering or the price that would be received
for any shares of Common Stock offered in such offering, then, notwithstanding
anything in Section 4(a) to the contrary, the Company shall only be required to
include in such registration, to the extent of the number of shares of Common
Stock which the Company is so advised can be sold in such offering, (i) first,
the number of shares of Common Stock proposed to be included in such
registration for the account of the Company and/or any stockholders of the
Company (other than the Investors) that have exercised demand registration
rights, in accordance with the priorities, if any, then existing among the
Company and/or such stockholders of the Company with registration rights (other
than the Investors), and (ii) second, the shares of Common Stock requested to be
included in such registration by all other stockholders of the Company who have
piggyback registration rights (including, without limitation, the Investors),
PRO RATA among such other stockholders (including,

                                       2
<PAGE>

without limitation, the Investors) on the basis of the number of shares of
Common Stock that each of them requested to be included in such registration.

         (c) In connection with any offering involving an underwriting of
shares, the Company shall not be required under Section 4 hereof or otherwise to
include the Registrable Shares of any Investor therein unless such Investor
accepts and agrees to the terms of the underwriting, which shall be reasonable
and customary, as agreed upon between the Company and the underwriters selected
by the Company.

         5. OBLIGATIONS OF THE COMPANY. In connection with the Company's
obligation under Sections 3 and 4 hereof to file the Registration Statement
with the SEC and to use reasonable efforts to cause the Registration
Statement to become effective as soon as practicable, the Company shall, as
expeditiously as reasonably possible:

         (a) Prepare and file with the SEC such amendments and supplements to
the Registration Statement and the prospectus used in connection therewith as
may be necessary to comply with the provisions of the Securities Act with
respect to the disposition of all Registrable Shares covered by the Registration
Statement;

         (b) Furnish to the selling Investors such number of copies of a
prospectus, including a preliminary prospectus, in conformity with the
requirements of the Securities Act, and such other documents (including, without
limitation, prospectus amendments and supplements as are prepared by the Company
in accordance with Section 5(a) above) as the selling Investors may reasonably
request in order to facilitate the disposition of such selling Investors'
Registrable Shares;

         (c) Notify the selling Investors, at any time when a prospectus
relating to the Registration Statement is required to be delivered under the
Securities Act, of the happening of any event as a result of which the
prospectus included in or relating to the Registration Statement contains an
untrue statement of a material fact or omits any fact necessary to make the
statements therein not misleading; and, thereafter, the Company will promptly
prepare (and, when completed, give notice to each selling Investor) a supplement
or amendment to such prospectus so that, as thereafter delivered to the
purchasers of such Registrable Shares, such prospectus will not contain an
untrue statement of a material fact or omit to state any fact necessary to make
the statements therein not misleading; PROVIDED that upon such notification by
the Company, the selling Investors will not offer or sell Registrable Shares
until the Company has notified the selling Investors that it has prepared a
supplement or amendment to such prospectus and delivered copies of such
supplement or amendment to the selling Investors (it being understood and agreed
by the Company that the foregoing proviso shall in no way diminish or otherwise
impair the Company's obligation to promptly prepare a prospectus amendment or
supplement as above provided in this Section 5(c) and deliver copies of same as
above provided in Section 5(b) hereof); and

         (d) Use commercially reasonable efforts to register and qualify the
Registrable Shares covered by the Registration Statement under such other
securities or Blue Sky laws of such jurisdictions as shall be reasonably
appropriate in the opinion of the Company and the managing underwriters, if any,
PROVIDED that the Company shall not be required in connection therewith or as a
condition thereto to qualify to do business or to file a general consent to
service of process in any such states or jurisdictions, and PROVIDED FURTHER
that (notwithstanding anything in this Agreement to the contrary with respect to
the bearing of expenses) if any jurisdiction in which any of such Registrable
Shares shall be qualified shall require that expenses incurred in connection
with the qualification therein of any such Registrable Shares be borne by the
selling Investors, then the selling Investors shall, to the extent required by
such jurisdiction, pay their PRO RATA share of such qualification expenses.

         6. FURNISH INFORMATION. It shall be a condition precedent to the
obligations of the Company to take any action pursuant to this Agreement that
the selling Investors shall furnish to the Company such information regarding
them and the securities held by them as the Company shall reasonably request and
as shall be required in order to effect any registration by the Company pursuant
to this Agreement.

         7. EXPENSES OF REGISTRATION. All expenses incurred in connection with
the registration of the Registrable Shares pursuant to this Agreement (excluding
underwriting, brokerage and other selling commissions and discounts), including
without limitation all registration and qualification and filing fees, printing,
and fees and disbursements of counsel for the Company, shall be borne by the
Company.

                                       3
<PAGE>

         8. DELAY OF REGISTRATION. The Investors shall not take any action to
restrain, enjoin or otherwise delay any registration as the result of any
controversy which might arise with respect to the interpretation or
implementation of this Agreement.

         9. INDEMNIFICATION.

         (a) To the extent permitted by law, the Company will indemnify and hold
harmless each selling Investor, any investment banking firm acting as an
underwriter for the selling Investors, any broker/dealer acting on behalf of any
selling Investors and each officer and director of such selling Investor, such
underwriter, such broker/dealer and each person, if any, who controls such
selling Investor, such underwriter or broker/dealer within the meaning of the
Securities Act, against any losses, claims, damages or liabilities, joint or
several, to which they may become subject under the Securities Act or otherwise,
insofar as such losses, claims, damages or liabilities (or actions in respect
thereof) arise out of or are based upon any untrue or alleged untrue statement
of any material fact contained in the Registration Statement, in any preliminary
prospectus or final prospectus relating thereto or in any amendments or
supplements to the Registration Statement or any such preliminary prospectus or
final prospectus, or arise out of or are based upon the omission or alleged
omission to state therein a material fact required to be stated therein, or
necessary to make the statements therein not misleading; and will reimburse such
selling Investor, such underwriter, broker/dealer or such officer, director or
controlling person for any legal or other expenses reasonably incurred by them
in connection with investigating or defending any such loss, claim, damage,
liability or action; PROVIDED, HOWEVER, that the indemnity agreement contained
in this Section 9(a) shall not apply to amounts paid in settlement of any such
loss, claim, damage, liability or action if such settlement is effected without
the consent of the Company (which consent shall not be unreasonably withheld),
nor shall the Company be liable in any such case for any such loss, damage,
liability or action to the extent that it arises out of or is based upon an
untrue statement or alleged untrue statement or omission made in connection with
the Registration Statement, any preliminary prospectus or final prospectus
relating thereto or any amendments or supplements to the Registration Statement
or any such preliminary prospectus or final prospectus, in reliance upon and in
conformity with written information furnished expressly for use in connection
with the Registration Statement or any such preliminary prospectus or final
prospectus by the selling Investors, any underwriter for them or controlling
person with respect to them.

         (b) To the extent permitted by law, each selling Investor will
severally and not jointly indemnify and hold harmless the Company, each of its
directors, each of its officers who have signed the Registration Statement, each
person, if any, who controls the Company within the meaning of the Securities
Act, any investment banking firm acting as underwriter for the Company or the
selling Investors, or any broker/dealer acting on behalf of the Company or any
selling Investors, and all other selling Investors against any losses, claims,
damages or liabilities to which the Company or any such director, officer,
controlling person, underwriter, or broker/dealer or such other selling Investor
may become subject to, under the Securities Act or otherwise, insofar as such
losses, claims, damages or liabilities (or actions in respect thereto) arise out
of or are based upon any untrue or alleged untrue statement of any material fact
contained in the Registration Statement or any preliminary prospectus or final
prospectus, relating thereto or in any amendments or supplements to the
Registration Statement or any such preliminary prospectus or final prospectus,
or arise out of or are based upon the omission or alleged omission to state
therein a material fact required to be stated therein or necessary to make the
statements therein not misleading, in each case to the extent and only to the
extent that such untrue statement or alleged untrue statement or omission or
alleged omission was made in the Registration Statement, in any preliminary
prospectus or final prospectus relating thereto or in any amendments or
supplements to the Registration Statement or any such preliminary prospectus or
final prospectus, in reliance upon and in conformity with written information
furnished by the selling Investor expressly for use in connection with the
Registration Statement, or any preliminary prospectus or final prospectus; and
such selling Investor will reimburse any legal or other expenses reasonably
incurred by the Company or any such director, officer, controlling person,
underwriter, broker/dealer or other selling Investor in connection with
investigating or defending any such loss, claim, damage, liability or action,
PROVIDED, HOWEVER, that the liability of each selling Investor hereunder shall
be limited to the proceeds (net of underwriting discounts and commissions, if
any) received by such selling Investor from the sale of Registrable Shares
covered by the Registration Statement, and PROVIDED, FURTHER, HOWEVER, that the
indemnity agreement contained in this Section 9(b) shall not apply to amounts
paid in settlement of any such loss, claim, damage, liability or action if such
settlement is effected without the consent of those selling Investor(s) against
which the request for indemnity is being made (which consent shall not be
unreasonably withheld).

         (c) Promptly after receipt by an indemnified party under this Section 9
of notice of the commencement of any action, such indemnified party will, if a
claim in respect thereof is to be made against any indemnifying party

                                       4
<PAGE>

under this Section 9, notify the indemnifying party in writing of the
commencement thereof and the indemnifying party shall have the right to
participate in and, to the extent the indemnifying party desires, jointly with
any other indemnifying party similarly noticed, to assume at its expense the
defense thereof with counsel mutually satisfactory to the indemnifying parties
with the consent of the indemnified party which consent will not be unreasonably
withheld, conditioned or delayed. In the event that the indemnifying party
assumes any such defense, the indemnified party may participate in such defense
with its own counsel and at its own expense, PROVIDED, HOWEVER, that the counsel
for the indemnifying party shall act as lead counsel in all matters pertaining
to such defense or settlement of such claim and the indemnifying party shall
only pay for such indemnified party's expenses for the period prior to the date
of its participation in such defense. The failure to notify an indemnifying
party promptly of the commencement of any such action, if prejudicial to his
ability to defend such action, shall relieve such indemnifying party of any
liability to the indemnified party under this Section 9, but the omission so to
notify the indemnifying party will not relieve him of any liability which he may
have to any indemnified party otherwise other than under this Section 9.

         (d) Notwithstanding anything to the contrary herein, the indemnifying
party shall not be entitled to settle any claim, suit or proceeding unless in
connection with such settlement the indemnified party receives an unconditional
release with respect to the subject matter of such claim, suit or proceeding and
such settlement does not contain any admission of fault by the indemnified
party.

         10. REPORTS UNDER THE EXCHANGE ACT. With a view to making available to
the Investors the benefits of Rule 144 and any other rule or regulation of the
SEC that may at any time permit the Investors to sell the Purchased Shares to
the public without registration, the Company agrees to use commercially
reasonable efforts: (i) to make and keep public information available, as those
terms are understood and defined in the General Instructions to Form S-3, or any
successor or substitute form, and in Rule 144, (ii) to file with the SEC in a
timely manner all reports and other documents required to be filed by an issuer
of securities registered under the Securities Act or the Exchange Act, (iii) as
long as any Investor owns any Purchased Shares, to furnish in writing upon such
Investor's request a written statement by the Company that it has complied with
the reporting requirements of Rule 144 and of the Securities Act and the
Exchange Act, and to furnish to such Investor a copy of the most recent annual
or quarterly report of the Company, and such other reports and documents so
filed by the Company as may be reasonably requested in availing such Investor of
any rule or regulation of the SEC permitting the selling of any such Purchased
Shares without registration and (iv) undertake any additional actions reasonably
necessary to maintain the availability of the Registration Statement or the use
of Rule 144.

         11. DEFERRAL. Notwithstanding anything in this Agreement to the
contrary, if the Company shall furnish to the selling Investors a certificate
signed by the President or Chief Executive Officer of the Company stating that
the Board of Directors of the Company has made the good faith determination (i)
that continued use by the selling Investors of the Registration Statement for
purposes of effecting offers or sales of Registrable Shares pursuant thereto
would require, under the Securities Act, premature disclosure in the
Registration Statement (or the prospectus relating thereto) of material,
nonpublic information concerning the Company, its business or prospects or any
proposed material transaction involving the Company, (ii) that such premature
disclosure would be materially adverse to the Company, its business or prospects
or any such proposed material transaction or would make the successful
consummation by the Company of any such material transaction significantly less
likely and (iii) that it is therefore essential to suspend the use by the
Investors of such Registration Statement (and the prospectus relating thereto)
for purposes of effecting offers or sales of Registrable Shares pursuant
thereto, then the right of the selling Investors to use the Registration
Statement (and the prospectus relating thereto) for purposes of effecting offers
or sales of Registrable Shares pursuant thereto shall be suspended for a period
(the "Suspension Period") of not more than 90 days after delivery by the Company
of the certificate referred to above in this Section 11. During the Suspension
Period, none of the Investors shall offer or sell any Registrable Shares
pursuant to or in reliance upon the Registration Statement (or the prospectus
relating thereto).

         12. TRANSFER OF REGISTRATION RIGHTS. None of the rights of any Investor
under this Agreement shall be transferred or assigned to any person unless (i)
such person is a Qualifying Holder (as defined below), and (ii) such person
agrees to become a party to, and bound by, all of the terms and conditions of,
this Agreement by duly executing and delivering to the Company an Instrument of
Adherence in the form attached as EXHIBIT B hereto. For purposes of this Section
12, the term "QUALIFYING HOLDER" shall mean, with respect to any Investor, (i)
any partner thereof, (ii) any corporation, partnership controlling, controlled
by, or under common control with, such Investor or any partner thereof, or (iii)
any other direct transferee from such Investor of at least 50% of those
Registrable Shares held or that may be acquired by such Investor. None of the
rights of any Investor under this

                                       5
<PAGE>

Agreement shall be transferred or assigned to any Person (including, without
limitation, a Qualifying Holder) that acquires Registrable Shares in the event
that and to the extent that such Person is eligible to resell such Registrable
Shares pursuant to Rule 144(k) of the Securities Act or may otherwise resell
such Registrable Shares pursuant to an exemption from the registration
provisions of the Securities Act.

         13. ENTIRE AGREEMENT. This Agreement constitutes and contains the
entire agreement and understanding of the parties with respect to the subject
matter hereof, and it also supersedes any and all prior negotiations,
correspondence, agreements or understandings with respect to the subject matter
hereof.

         14. MISCELLANEOUS.

         (a) This Agreement may not be amended, modified or terminated, and no
rights or provisions may be waived, except with the written consent of the
Majority Holders and the Company.

         (b) This Agreement shall be governed by and construed and enforced in
accordance with the laws of the Commonwealth of Massachusetts, and shall be
binding upon and inure to the benefit of the parties hereto and their respective
heirs, personal representatives, successors or assigns, PROVIDED that the terms
and conditions of Section 12 hereof are satisfied. This Agreement shall also be
binding upon and inure to the benefit of any transferee of any of the Purchased
Shares PROVIDED that the terms and conditions of Section 12 hereof are
satisfied. Notwithstanding anything in this Agreement to the contrary, if at any
time any Investor shall cease to own any Purchased Shares, all of such
Investor's rights under this Agreement shall immediately terminate.

         (c) (i) Any notices, reports or other correspondence (hereinafter
collectively referred to as "CORRESPONDENCE") required or permitted to be given
hereunder shall be sent by courier (overnight or same day) or Fax or delivered
by hand to the party to whom such correspondence is required or permitted to be
given hereunder. The date of giving any notice shall be the date of its actual
receipt.

                  (ii)     All correspondence to the Company shall be addressed
         as follows:

                           Cubist Pharmaceuticals, Inc.
                           24 Emily Street
                           Cambridge, MA  02139
                           Attention:  Scott M. Rocklage,
                           President and Chief Executive Officer
                           Fax: (617) 576-0232

                           with a copy to:

                           Bingham Dana LLP
                           150 Federal Street
                           Boston, MA  02110

                           Attention:  Justin P. Morreale, Esq.
                                           and
                                       Julio E. Vega, Esq.
                           Fax:  (617) 951-8736

                  (iii) All correspondence to any Investor shall be sent to such
         Purchaser at the address set forth in EXHIBIT A.

         (d) Any entity may change the address to which correspondence to it is
to be addressed by notification as provided for herein.

         (e) The parties acknowledge and agree that in the event of any breach
of this Agreement, remedies at law may be inadequate, and each of the parties
hereto shall be entitled to seek specific performance of the obligations of the
other parties hereto and such appropriate injunctive relief as may be granted by
a court of competent jurisdiction.

                                       6
<PAGE>

         (f) This Agreement may be executed in a number of counterparts, any of
which together shall for all purposes constitute one Agreement, binding on all
the parties hereto notwithstanding that all such parties have not signed the
same counterpart.

      [Remainder of page intentionally left blank. Signature pages follow.]

                                       7
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Registration
Rights Agreement as of the date and year first above written.

                                CUBIST PHARMACEUTICALS, INC.

                                By:   /s/ Scott M. Rocklage
                                    ----------------------------------------
                                Name: Scott M. Rocklage
                                Title: President and Chief Executive Officer

                 [Investor Counterpart Signature Pages Follow.]

                                       8
<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                                       INVESTOR:

                                       DVG DEUTSCHE
                                       VERMOGENSBILDUNGSGESELLSCHAFT
                                       Print Name of Investor

                                        /s/  Reichert Horn
                                       -----------------------------------
                                       Signature or Authorized Person
                                       Print Name:        Reichert Horn
                                                   -----------------------
                                       Print Title:
                                                   -----------------------

                                        Address:
                                                 Mainzer Landstrasse 16
                                                 -------------------------
                                                 60255 Frankfurt, Germany
                                                 -------------------------

                                                 -------------------------

                                                 -------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                                       INVESTOR:

                                       DEUTSCHE ASSET
                                       MANAGEMENTINVESTMENTGESELLSCHAFT MBH
                                       ON BEHALF OF DIRFONDS, AP
                                       Print Name of Investor

                                        /s/  Reichert Horn
                                       -----------------------------------
                                       Signature or Authorized Person
                                       Print Name:        Reichert Horn
                                                   -----------------------
                                       Print Title:
                                                   -----------------------

                                        Address:
                                                 Mainzer Landstrasse 16
                                                 -------------------------
                                                 60255 Frankfurt, Germany
                                                 -------------------------

                                                 -------------------------

                                                 -------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                                       INVESTOR:

                                       DEUTSCHE ASSET MANAGEMENT
                                       INVESTMENTGESELLSCHAFT MBH
                                       ON BEHALF OF NAVAP
                                       Print Name of Investor

                                        /s/  Reichert Horn
                                       -----------------------------------
                                       Signature or Authorized Person
                                       Print Name:        Reichert Horn
                                                   -----------------------
                                       Print Title:
                                                   -----------------------

                                        Address:
                                                 Mainzer Landstrasse 16
                                                 -------------------------
                                                 60255 Frankfurt, Germany
                                                 -------------------------

                                                 -------------------------

                                                 -------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            CHELSEY CAPITAL
                            Print Name of Investor

                             /s/  Stuart Feldman
                            --------------------------------------
                            Signature or Authorized Person
                            Print Name:     Stuart Feldman
                                        --------------------------
                            Print Title:     President
                                        --------------------------
                             Address:
                                      1370 Avenue of the Americas
                                      ----------------------------
                                      Suite 2603
                                      ----------------------------
                                      New York, NY 10019
                                      ----------------------------

                                      ----------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            CROSSLINK CROSSOVER FUND III, L.P.
                            Print Name of Investor

                             /s/  Michael J. Stark
                            -----------------------------------
                            Signature or Authorized Person
                            Print Name:     Michael J. Stark
                                        -----------------------
                            Print Title:    Managing Director
                                        -----------------------
                             Address:
                                      555 California Street
                                      -------------------------
                                      San Francisco, CA 94104
                                      -------------------------

                                      -------------------------

                                      -------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            DELAWARE MANAGEMENT COMPANY,
                            INVESTMENT  ADVISER ON BEHALF OF PACE
                            SMALL/MEDIUM COMPANY GROWTH EQUITY
                            INVESTMENTS
                            Print Name of Investor

                             /s/  Stuart M. George
                            -----------------------------------
                            Signature or Authorized Person
                            Print Name:     Stuart M. George
                                        -----------------------
                            Print Title:     Vice President
                                        -----------------------
                             Address:
                                      2005 Market Street
                                      -------------------------
                                      Philadelphia, PA 19103
                                      -------------------------

                                      -------------------------

                                      -------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            DELAWARE GROUP EQUITY FUNDS III, ON
                            BEHALF OF ITS DELAWARE TREND FUND
                            Print Name of Investor

                             /s/  Gerald S. Frey
                            -----------------------------------
                            Signature or Authorized Person
                            Print Name:     Gerald S. Frey
                                        -----------------------
                            Print Title: Senior Vice President
                                        -----------------------
                             Address:
                                      2005 Market Street
                                      -------------------------
                                      Philadelphia, PA 19103
                                      -------------------------

                                      -------------------------

                                      -------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            DELAWARE POOLED TRUST, ON BEHALF
                            OF ITS THE SMALL-CAP GROWTH EQUITY
                            PORTFOLIO
                            Print Name of Investor

                             /s/  Gerald S. Frey
                            -----------------------------------
                            Signature or Authorized Person
                            Print Name:     Gerald S. Frey
                                        -----------------------
                            Print Title: Senior Vice President
                                        -----------------------
                             Address:
                                      2005 Market Street
                                      -------------------------
                                      Philadelphia, PA 19103
                                      -------------------------

                                      -------------------------

                                      -------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            DELAWARE GROUP PREMIUM FUND,
                            ON BEHALF OF ITS TREND SERIES
                            Print Name of Investor

                             /s/  Gerald S. Frey
                            -----------------------------------
                            Signature or Authorized Person
                            Print Name:     Gerald S. Frey
                                        -----------------------
                            Print Title: Senior Vice President
                                        -----------------------
                             Address:
                                      2005 Market Street
                                      -------------------------
                                      Philadelphia, PA 19103
                                      -------------------------

                                      -------------------------

                                      -------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            DEUTSCHE GESELLSCHAFT FUR
                            WERTPAPIERSPAREN, FRANKFURT
                            Print Name of Investor

                             /s/   Michael Sistenich
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   Michael Sistenich
                                        ------------------------------
                            Print Title: Senior Fund Manager
                                        ------------------------------
                             Address:
                                      Gruneburgweg 113-115
                                      --------------------------------
                                      60323 Frankfurt Au Main, Germany
                                      --------------------------------

                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            FRANKLIN AGGRESSIVE GROWTH FUND #462
                            Print Name of Investor

                             /s/   Kurt Von Emster
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   Kurt Von Emster
                                        ------------------------------
                            Print Title: VP, Franklin Advisers
                                        ------------------------------
                             Address:
                                      777 Mariners Island Blvd.
                                      --------------------------------
                                      San Mateo, CA 94404
                                      --------------------------------

                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            FRANKLIN BIOTECH DISCOVERY FUND #402
                            Print Name of Investor

                             /s/   Kurt Von Emster
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   Kurt Von Emster
                                        ------------------------------
                            Print Title: VP, Franklin Advisers
                                        ------------------------------
                             Address:
                                      777 Mariners Island Blvd.
                                      --------------------------------
                                      San Mateo, CA 94404
                                      --------------------------------

                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            FRANKLIN GLOBAL HEALTHCARE FUND #199
                            Print Name of Investor

                             /s/   Kurt Von Emster
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   Kurt Von Emster
                                        ------------------------------
                            Print Title: VP, Franklin Advisers
                                        ------------------------------
                             Address:
                                      777 Mariners Island Blvd.
                                      --------------------------------
                                      San Mateo, CA 94404
                                      --------------------------------

                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            RS PACIFIC PARTNERS
                            Print Name of Investor

                             /s/   James L. Callinan
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   James L. Callinan
                                        ------------------------------
                            Print Title: Chief Investment Officer
                                        ------------------------------
                             Address:
                                      RS Investment Management
                                      --------------------------------
                                      388 Market Street, Suite 200
                                      --------------------------------
                                      San Francisco, CA 94111
                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            RS PACIFIC PARTNERS LP ONSHORE
                            Print Name of Investor

                             /s/   James L. Callinan
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   James L. Callinan
                                        ------------------------------
                            Print Title: Chief Investment Officer
                                        ------------------------------
                             Address:
                                      RS Investment Management
                                      --------------------------------
                                      388 Market Street, Suite 200
                                      --------------------------------
                                      San Francisco, CA 94111
                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            RS EMERGING GROWTH PARTNERS LP
                            Print Name of Investor

                             /s/   James L. Callinan
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   James L. Callinan
                                        ------------------------------
                            Print Title: Chief Investment Officer
                                        ------------------------------
                             Address:
                                      RS Investment Management
                                      --------------------------------
                                      388 Market Street, Suite 200
                                      --------------------------------
                                      San Francisco, CA 94111
                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            RS PREMIUM PARTNERS LP
                            Print Name of Investor

                             /s/   James L. Callinan
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   James L. Callinan
                                        ------------------------------
                            Print Title: Chief Investment Officer
                                        ------------------------------
                             Address:
                                      RS Investment Management
                                      --------------------------------
                                      388 Market Street, Suite 200
                                      --------------------------------
                                      San Francisco, CA 94111
                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            PAISLEY FUND LP
                            Print Name of Investor

                             /s/   James L. Callinan
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   James L. Callinan
                                        ------------------------------
                            Print Title: Chief Investment Officer
                                        ------------------------------
                             Address:
                                      RS Investment Management
                                      --------------------------------
                                      388 Market Street, Suite 200
                                      --------------------------------
                                      San Francisco, CA 94111
                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            PAISLEY FUND LP
                            Print Name of Investor

                             /s/   James L. Callinan
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   James L. Callinan
                                        ------------------------------
                            Print Title: Chief Investment Officer
                                        ------------------------------
                             Address:
                                      RS Investment Management
                                      --------------------------------
                                      388 Market Street, Suite 200
                                      --------------------------------
                                      San Francisco, CA 94111
                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            ENDEAVOR FUND, LLC
                            Print Name of Investor

                             /s/   Stephen J. Shenkenberg
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   Stephen J. Shenkenberg
                                        ------------------------------
                            Print Title: Vice President
                                        ------------------------------
                             Address:
                                      100 Heritage Reserve
                                      --------------------------------
                                      Menomonee Falls, WI 53051
                                      --------------------------------

                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            STONG SPECIAL INVESTMENT, L.P.
                            Print Name of Investor

                             /s/   Stephen J. Shenkenberg
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   Stephen J. Shenkenberg
                                        ------------------------------
                            Print Title: Vice President
                                        ------------------------------
                             Address:
                                      100 Heritage Reserve
                                      --------------------------------
                                      Menomonee Falls, WI 53051
                                      --------------------------------

                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            ENDEAVOR OFFSHORE FUND LTD
                            Print Name of Investor

                             /s/   Stephen J. Shenkenberg
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   Stephen J. Shenkenberg
                                        ------------------------------
                            Print Title: Vice President
                                        ------------------------------
                             Address:
                                      100 Heritage Reserve
                                      --------------------------------
                                      Menomonee Falls, WI 53051
                                      --------------------------------

                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            STRONG DISCOVERY FUND II, A SERIES
                            OF STRONG VARIABLE INSURANCE
                            FUNDS, INC.
                            Print Name of Investor

                             /s/   Stephen J. Shenkenberg
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   Stephen J. Shenkenberg
                                        ------------------------------
                            Print Title: Vice President
                                        ------------------------------
                             Address:
                                      100 Heritage Reserve
                                      --------------------------------
                                      Menomonee Falls, WI 53051
                                      --------------------------------

                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            STRONG DISCOVERY FUND, INC.
                            Print Name of Investor

                             /s/   Stephen J. Shenkenberg
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   Stephen J. Shenkenberg
                                        ------------------------------
                            Print Title: Vice President
                                        ------------------------------
                             Address:
                                      100 Heritage Reserve
                                      --------------------------------
                                      Menomonee Falls, WI 53051
                                      --------------------------------

                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            HARBOUR HOLDING LTD.
                            Print Name of Investor

                             /s/   Stephen J. Shenkenberg
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   Stephen J. Shenkenberg
                                        ------------------------------
                            Print Title: Vice President
                                        ------------------------------
                             Address:
                                      100 Heritage Reserve
                                      --------------------------------
                                      Menomonee Falls, WI 53051
                                      --------------------------------

                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            ACTIVEST MANAGEMENT SA
                            Print Name of Investor

                             /s/   Simon Aeschbacher
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   Simon Aeschbacher
                                        ------------------------------
                            Print Title:  Director
                                        ------------------------------
                             Address:
                                      12 Rue Ceard
                                      --------------------------------
                                      1204 Geneve, Switzerland
                                      --------------------------------

                                      --------------------------------

                                      --------------------------------

<PAGE>

                       INVESTOR COUNTERPART SIGNATURE PAGE

                            INVESTOR:

                            ACTIVEST AMERICAN PERFORMANCE LIMITED
                            Print Name of Investor

                             /s/   Simon Aeschbacher
                            ------------------------------------------
                            Signature or Authorized Person
                            Print Name:   Simon Aeschbacher
                                        ------------------------------
                            Print Title:  Director
                                        ------------------------------
                             Address:
                                      12 Rue Ceard
                                      --------------------------------
                                      1204 Geneve, Switzerland
                                      --------------------------------

                                      --------------------------------

                                      --------------------------------

<PAGE>

                                    EXHIBIT A

                                    INVESTORS

<TABLE>
<CAPTION>
                                                                        Number of
                                                                        Shares                Total
Purchaser                                                               to be Purchased       Purchase Price
---------                                                               ---------------       --------------
<S>                                                                     <C>                   <C>

DVG DEUTSCHE                                                            200,000               US$5,000,000
VERMOGENSBILDUNGSGESELLSCHAFT

DEUTSCHE ASSET MANAGEMENT                                               100,000               US$2,500,000
INVESTMENTGESELLSCHAFT MBH
On behalf of  DIRFONDS, AP

DEUTSCHE ASSET MANAGEMENT                                               200,000               US$5,000,000
INVESTMENTGESELLSCHAFT MBH
On behalf of NAVAP

CHELSEY CAPITAL                                                         300,000               US$7,500,000

CROSSLINK CROSSOVER FUND III, L.P.                                      100,000               US$2,500,000

DELAWARE MANAGEMENT COMPANY                                             31,700                US$792,500
On behalf of PACE SMALL/MEDIUM COMPANY
GROWTH EQUITY INVESTMENTS

DELAWARE GROUP EQUITY FUNDS III                                         110,200               US$2,755,000
On behalf of DELAWARE TREND FUND

DELAWARE POOLED TRUST                                                   800                   US$20,000
On behalf of THE SMALL-CAP GROWTH EQUITY
PORTFOLIO

DELAWARE GROUP PREMIUM FUND                                             57,300                US$1,432,500
On behalf of TREND SERIES

DEUTSCHE GESELLSCHAFT FUR                                               200,000               US$5,000,000
WERTPAPIERSPAREN, FRANKFURT

FRANKLIN AGGRESSIVE GROWTH FUND #462                                    75,000                US$1,875,000

FRANKLIN BIOTECH DISCOVERY FUND #402                                    250,000               US$6,250,000

FRANKLIN GLOBAL HEALTH CARE FUND #199                                   50,000                US$1,250,000
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
                                                                        Number of
                                                                        Shares                Total
Purchaser                                                               to be Purchased       Purchase Price
---------                                                               ---------------       --------------
<S>                                                                     <C>                   <C>
RS PACIFIC PARTNERS                                                     57,253                US$1,431,325

RS PACIFIC PARTNERS LP ONSHORE                                          276                   US$6,900

RS EMERGING GROWTH PARTNERS LP                                          27,651                US$691,275

RS PREMIUM PARTNERS LP                                                  34,820                US$870,500

PAISLEY PACIFIC FUND                                                    60,000                US$1,500,000

THE PAISLEY FUND LP                                                     20,000                US$500,000

ENDEAVOR FUND LLC                                                       57,200                US$1,430,000

STRONG SPECIAL INVESTMENT LP                                            34,800                US$870,000

ENDEAVOR OFFSHORE FUND LTD                                              8,700                 US$217,500

STRONG DISCOVERY FUND II, a Series of                                   44,100                US$1,102,500
Strong Variable Insurance Funds, Inc.

STRONG DISCOVERY FUND, INC.                                             54,000                US$1,350,000

HARBOUR HOLDING LTD                                                     26,200                US$655,000

ACTIVEST MANAGEMENT SA                                                  70,000                US$1,750,000

ACTIVEST AMERICAN PERFORMANCE LIMITED                                   30,000                US$750,000
                                                                        --------------        ----------------
                          Total:                                        2,200,000             US$55,000,000
</TABLE>

<PAGE>

                                    EXHIBIT B

                          CUBIST PHARMACEUTICALS, INC.

                             INSTRUMENT OF ADHERENCE

Reference is hereby made to that certain Registration Rights Agreement, dated as
of ______________ ___, 2000, among Cubist Pharmaceuticals, Inc., a Delaware
corporation (the "COMPANY"), the Initial Investors and the Investor Permitted
Transferees, as amended and in effect from time to time (the "REGISTRATION
RIGHTS AGREEMENT"). Capitalized terms used herein without definition shall have
the respective meanings ascribed thereto in the Registration Rights Agreement.

         The undersigned, in order to become the owner or holder of
[___________] shares of common stock, par value $0.001 per share (the "COMMON
STOCK"), of the Company, hereby agrees that, from and after the date hereof, the
undersigned has become a party to the Registration Rights Agreement in the
capacity of an Investor Permitted Transferee, and is entitled to all of the
benefits under, and is subject to all of the obligations, restrictions and
limitations set forth in, the Registration Rights Agreement that are applicable
to Investor Permitted Transferees. This Instrument of Adherence shall take
effect and shall become a part of the Registration Rights Agreement immediately
upon execution.

         Executed under seal as of the date set forth below under the laws of
the Commonwealth of Massachusetts.

                                            Signature: _________________________
                                                         Name:
                                                         Title:

Accepted:

CUBIST PHARMACEUTICALS, INC.

By: _____________________________
      Name:
      Title:

Date: ___________________

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00001-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00001-of-00352.parquet"}]]