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                                                                   EXHIBIT 10.10


                            STOCK PURCHASE AGREEMENT

This STOCK PURCHASE AGREEMENT is dated as of the 26th day of January, 2000 by
and among Healtheon/WebMD Corporation, a Delaware corporation with its principal
office at 400 The Lenox Building, 3399 Peachtree Road NE, Atlanta, Georgia 30326
(the "Company"), and Janus Capital Corporation ("Janus").

         WHEREAS, the Company desires to issue and sell to Janus pursuant to
this Agreement shares (the "Shares") of the authorized but unissued shares of
common stock, $.0001 par value per share, of the Company (the "Common Stock");
and

         WHEREAS, Janus, wishes to purchase the Shares on the terms and subject
to the conditions set forth in this Agreement.

         NOW THEREFORE, in consideration of the mutual agreements,
representations, warranties and covenants herein contained, the parties hereto
agree as follows:

         1.       Definitions. As used in this Agreement, the following terms
shall have the following respective meanings:

                  (a)      "Affiliate" of a party means any corporation or other
         business entity controlled by, controlling or under common control with
         such party. For this purpose "control" shall mean direct or indirect
         beneficial ownership of fifty percent (50%) or more of the voting
         interest in such corporation or other business entity.

                  (b)      "Assets" of a Person shall mean all of the assets,
         properties, businesses and rights of such Person of every kind, nature,
         character and description, whether real, personal or mixed, tangible or
         intangible, accrued or contingent, or otherwise relating to or utilized
         in such Person's business, directly or indirectly, in whole or in part,
         whether or not carried on the books and records of such Person, and
         whether or not owned in the name of such Person or any Affiliate of
         such Person and wherever located.

                  (c)      "Closing Date" means the date of the Closing.

                  (d)      "Consent" shall mean any consent, approval,
         authorization, clearance, exemption, waiver, or similar affirmation by
         any Person pursuant to any Contract, Law, Order, or Permit.

                  (e)      "Contract" shall mean any written or oral agreement,
         arrangement, commitment, contract, indenture, instrument, lease,
         obligation, plan, restriction, understanding or undertaking of any kind
         or character, or other document to which any Person is a party or by
         which such Person is bound or affecting such Person's capital stock,
         Assets or business.

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                  (f)      "Exchange Act" means the Securities Exchange Act of
         1934, as amended, and all of the rules and regulations promulgated
         thereunder.

                  (g)      "Governmental Entity" shall mean any government or
         any agency, bureau, board, directorate, commission, court, department,
         official, political subdivision, tribunal, or other instrumentality of
         any government, whether federal, state or local, domestic or foreign.

                  (h)      "HSR Act" shall mean Section 7A of the Clayton Act,
         as added by Title II of the Hart-Scott-Rodino Antitrust Improvements
         Act of 1976, as amended, and the rules and regulations promulgated
         thereunder.

                  (i)      "Knowledge" shall mean with respect to any Party,
         with respect to any matter in question, that any of the Chief Executive
         Officer, Chief Financial Officer, General Counsel or Controller of such
         Party, has actual knowledge of such matter.

                  (j)      "Law" shall mean any code, law, ordinance,
         regulation, reporting or licensing requirement, rule, or statute
         applicable to a Person or its Assets, Liabilities or business,
         including those promulgated, interpreted or enforced by any Regulatory
         Authority.

                  (k)      "Litigation" shall mean any action, suit,
         arbitration, filed cause of action, filed claim, filed complaint,
         criminal prosecution, demand letter, governmental or other examination
         or investigation, hearing, inquiry, administrative or other proceeding,
         or notice (written or oral) by any Person alleging potential Liability
         or requesting information relating to or affecting a Party, its
         business, its Assets (including Contracts related to it), or the
         transactions contemplated by this Agreement.

                  (l)      "Material" for purposes of this Agreement shall be
         determined in light of the facts and circumstances of the matter in
         question; provided that any specific monetary amount stated in this
         Agreement shall determine materiality in that instance.

                  (m)      "Material Adverse Effect" on a Party shall mean an
         event, change or occurrence which, individually or together with any
         other event, change or occurrence, has a Material adverse impact on (i)
         the financial position, business, or results of operations of such
         Party and its Subsidiaries, taken as a whole, or (ii) the ability of
         such Party to perform its obligations under this Agreement or to
         consummate the other transactions contemplated by this Agreement;
         provided that "Material Adverse Effect" shall not be deemed to include
         events, changes or occurrences (x) generally affecting the healthcare
         information technology industry, or (y) generally affecting the overall
         U.S. economy.

                  (n)      "Order" shall mean any administrative decision or
         award, decree, injunction, judgment, order, quasi-judicial decision or
         award, ruling, or writ of


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         any federal, state, local or foreign or other court, arbitrator,
         mediator, tribunal, administrative agency or Regulatory Authority.

                  (o)      "Permit" shall mean any federal, state, local, and
         foreign governmental approval, authorization, certificate, consent,
         easement, filing, franchise, letter of good standing, license, notice,
         permit, qualification, registration or right of or from any
         Governmental Entity (or any extension, modification, amendment or
         waiver of any of these) to which any Person is a party or that is or
         may be binding upon or inure to the benefit of any Person or its
         securities, Assets or business, or any notice, statement, filing or
         other communication to be filed with or delivered to any Governmental
         Entity.

                   (p)     "Person" shall mean a natural person or any legal,
          commercial or Governmental Entity, such as, but not limited to, a
          corporation, general partnership, joint venture, limited partnership,
          limited liability company, trust, business association, group acting
          in concert, or any person acting in a representative capacity.

                  (q)      "Registration Rights Agreement" shall mean that
         certain Registration Rights Agreement, dated as of the date hereof,
         among the Company and the Janus.

                   (r)     "Regulatory Authorities" shall mean, collectively,
         the Federal Trade Commission, the United States Department of Justice,
         and all foreign, federal, state and local regulatory agencies and other
         Governmental Entities or bodies having jurisdiction over the Parties
         and their respective Assets, employees, businesses and/or Subsidiaries,
         including the NASD and the SEC.

                  (s)      "SEC" shall mean the Securities and Exchange
         Commission.

                  (t)      "Securities Act" shall mean the Securities Act of
         1933, as amended, and all of the rules and regulations promulgated
         thereunder.

                  (u)      "Subsidiaries" shall mean all those corporations,
         partnerships, associations, or other entities of which the entity in
         question owns or controls 50% or more of the outstanding equity
         securities either directly or through an unbroken chain of entities as
         to each of which 50% or more of the outstanding equity securities is
         owned directly or indirectly by its parent; provided, there shall not
         be included any such entity acquired through foreclosure or any such
         entity the equity securities of which are owned or controlled in a
         fiduciary capacity.


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         2.       Purchase and Sale of Shares.

         2.1      Purchase and Sale. Subject to and upon the terms and
conditions set forth in this Agreement, the Company agrees to issue and sell to
Janus, and Janus, hereby agrees to purchase from the Company, at the Closing,
15,000,000 shares of Common Stock at a purchase price of $62.00 per share. The
total purchase price payable by Janus for the shares of Common Stock that Janus
is hereby agreeing to purchase is 930,000,000.

         2.2      Closing. The closing of the transactions contemplated under
this Agreement (the "Closing") shall take place on the second business day after
the execution of this Agreement by the Company and Janus. Upon Closing, the
Company shall deliver the Common Stock purchased by Janus to Janus's custodian
via electronic delivery, registered in the name of Janus (or in such nominee or
custodial name as shall be specified by Janus), against payment of the purchase
price therefor by wire transfer of immediately available funds to such account
or accounts as the Company shall designate in writing.

         3.       Representations and Warranties of the Company

         The Company represents and warrants to Janus as follows:

         3.1      Organization, Standing, and Power. The Company is a
corporation duly organized, validly existing, and in good standing under the
Laws of the State of Delaware, and has the power and authority to carry on its
business as it has been and is now being conducted. The Company and each of its
Subsidiaries is duly qualified or licensed to transact business as a foreign
corporation and is in good standing in all jurisdictions where the character of
its Assets or the nature or conduct of its business requires it to be so
qualified or licensed, except for such jurisdictions in which the failure to be
so qualified or licensed would not have, individually or in the aggregate, a
Material Adverse Effect on the Company. Copies of the Certificate of
Incorporation and all amendments thereto of the Company and the bylaws, as
amended, of the Company and copies of all resolutions adopted and action taken
by the stockholders or Board of Directors and all committees thereof of the
Company, which have been made available to Janus for review, are true and
complete in all Material respects and accurately reflect all proceedings of the
stockholders and Board of Directors (and all committees thereof) of the Company.

         3.2      Authorization of Agreement; No Breach. The execution, delivery
and performance of this Agreement and the Registration Rights Agreement has been
duly authorized by all necessary corporate action of the Company. This Agreement
constitutes, and all agreements and other instruments and documents to be
executed and delivered by the Company pursuant to this Agreement, including the
Registration Rights Agreement, will constitute, legal, valid and binding
obligations of the Company enforceable against it in accordance with their
respective terms, except to the extent such enforceability is subject to (i)
laws of general application relating to bankruptcy, insolvency, moratorium and
the relief of debtors and (ii) the availability of specific


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performance, injunctive relief or other equitable remedies. Except in such case,
individually or in the aggregate, that will not result in a Material Adverse
Effect on the Company, the execution, delivery and performance of this Agreement
and the agreements and other documents and instruments to be executed and
delivered by the Company pursuant to this Agreement and the consummation of the
transactions contemplated hereby and thereby will not (i) violate or result in a
breach of or default under the certificate of incorporation or bylaws of the
Company or any of its Subsidiaries or any other Material Contract to which the
Company or any of its Subsidiaries is a party or is bound; (ii) to the Knowledge
of the Company and its Subsidiaries, violate any Law, Order, administrative
decision or award of any court, arbitrator, mediator, tribunal or Regulatory
Authority applicable to or binding upon the Company or its Subsidiaries or upon
their respective securities, Assets or business; or (iii) create a Material lien
upon the securities, Assets or business of the Company or any of its
Subsidiaries.

         3.3      Capital Stock.

                  (a)      As of November 11, 1999, the authorized capital stock
of the Company consists of: (i) 600,000,000 shares of the Common Stock, of which
146,204,261 shares (plus any shares issued upon exercise of the Company's
Options and Warrants (as defined in Section 3.3(b) since November 11, 1999) are
issued and outstanding and (ii) 5,000,000 shares of Preferred Stock, $0.0001 par
value per share, none of which shares are issued and outstanding. All of the
outstanding shares of the Common Stock have been duly authorized and validly
issued, and are fully paid and nonassessable, and were issued in Material
compliance with the Securities Act and applicable state securities Laws, except
to the extent that non-compliance would not have a Material Adverse Effect on
the Company.

                  (b)      As of November 11, 1999, an aggregate of 63,595,222
shares of the Common Stock (less any shares of Common Stock subject to the
Company's Options and Warrants that have been exercised since November 11, 1999)
are subject to issuance pursuant to outstanding options to purchase the Common
Stock under the Company's stock option plans and outstanding warrants to
purchase the Company's Common Stock. (Stock options granted by the Company
pursuant to its stock option plans and warrants are referred to in this
Agreement as the "Company Options and Warrants".) All Company Options and
Warrants were issued or granted in Material compliance with the Securities Act
and applicable state securities Laws pursuant to a valid exemption from
registration under the Securities Act and all applicable state securities Laws.

                  (c)      Except as set forth above, in the Company's SEC
Documents and in Section 3.3(c) of the Company Disclosure Letter, as of the date
of this Agreement, there are no subscriptions, options, warrants, equity
securities, partnership interests or similar ownership interests, calls, rights
(including preemptive rights), commitments or agreements of any character to
which the Company or any of its Subsidiaries is a party or by which it is bound
obligating the Company or any of its Subsidiaries to issue, deliver or sell, or
cause to be issued, delivered or sold, or repurchase, redeem or otherwise
acquire, or cause the repurchase, redemption or acquisition of, any shares of
capital stock, partnership interests or similar ownership interests of the
Company or any of its Subsidiaries or obligating the Company or any of its
Subsidiaries to grant, extend,


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accelerate the vesting of or enter into any such subscription, option, warrant,
equity security, call, right, commitment or agreement.

         3.4      The Company SEC Filings; Financial Statements. The Company has
filed various reports, schedules, forms, statements and other documents (which
are publicly available) with the SEC pursuant to applicable Securities Laws from
January 1, 1999 to the date of this Agreement (the "Company SEC Documents"), and
the Company SEC Documents constitute all of the documents required to have been
filed by the Company pursuant to such Laws for such period. As of their
respective dates, or if amended, as of the date of the last such amendment, the
Company SEC Documents complied in all Material respects, with the requirements
of the Securities Act or the Exchange Act, as the case may be, and none of the
Company SEC Documents contained when filed any untrue statement of a Material
fact or omitted, or will omit, to state any Material fact required to be stated
therein or necessary to make the statements therein, in light of the
circumstances under which they were made, or are to be made, not misleading.
Except to the extent information contained in any the Company SEC Document has
been revised or superseded by a later filed the Company SEC Document, none of
the Company SEC Documents (including any and all financial statements included
therein) contains any untrue statement of a Material fact or omits to state a
Material fact required to be stated therein or necessary in order to make the
statements therein, in the light of the circumstances under which they were
made, not misleading. The consolidated financial statements of the Company
included in the Company SEC Documents when filed fairly presented the
consolidated financial position of the Company and its consolidated Subsidiaries
as at the respective dates thereof and the consolidated results of their
operations and their consolidated cash flows for the respective periods then
ended (subject, in the case of unaudited statements, to normal year-end audit
adjustments and to any other adjustments described therein) and have been
prepared in conformity with GAAP (except, in the case of unaudited statements,
as permitted by Form 10-Q of the SEC) applied on a consistent basis during the
periods involved (except as may be indicated therein or in the notes thereto).

         3.5      Absence of Undisclosed Liabilities. Except as disclosed on the
Company SEC Documents, the Company does not have any Material (individually or
in the aggregate) Liabilities, other than Liabilities incurred in the ordinary
course of business since September 30, 1999 or Liabilities arising under this
Agreement.

         3.6      Absence of Certain Changes or Events. Since September 30,
1999, there has not occurred (i) any events, changes or occurrences (other than
events or condition affecting the economy generally) which have had, or are
reasonably likely to have, individually or in the aggregate, a Material Adverse
Effect on the Company, (ii) any declaration, setting aside or payment of any
dividend or distribution of any kind by the Company on any class of its capital
stock or (iii) any change in the Company's accounting methods, principles or
practices utilized by or affecting the Company except as required by concurrent
changes in GAAP.

         3.7      Compliance with Laws. The business of the Company has been and
is being conducted in compliance with all applicable Laws, except for violations
or failures to so comply that could not reasonably be expected, individually or
in the aggregate, to


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have Material Adverse Effect on the Company; and no investigation or review by
any Governmental Entity with respect to the Company is pending or, to the
Knowledge of the Company, threatened in writing, other than, in each case, those
which could not reasonably be expected, individually or in the aggregate, to
have a Material Adverse Effect on the Company.

         3.8      Governmental Approvals; Required Consents. No filing or
registration with, or Consent of, any Governmental Entity or any other third
party is required by or with respect to the Company in connection with the
execution and delivery of this Agreement or is necessary for the consummation of
the transactions contemplated hereby except such other Consents, registrations
and filings the failure of which to obtain or make could not reasonably be
expected, individually or in the aggregate, to have a Material Adverse Effect on
the Company.

         3.9      The Company Common Stock. The Company's Common Stock to be
issued in accordance with the terms and provisions of this Agreement will, when
so issued, be duly authorized, validly issued, fully paid and non-assessable.

         3.10     Orders and Litigation. Except as set forth in the Company SEC
Documents, there are no outstanding Orders against the Company or any of its
Subsidiaries, any of their Assets or business, or, to the Knowledge of the
Company, any of the Company's or its Subsidiaries' current or former directors
or officers (during the period served as such) or any other person whom the
Company or any of its Subsidiaries has agreed to indemnify, as such. Except as
set forth in the Company SEC Documents, there is no Material Litigation pending
or, to the Knowledge of the Company, threatened in writing against the Company
or any of its Subsidiaries, any of their Assets or business, or, to the
Knowledge of the Company, any of the Company's or its Subsidiaries' current or
former directors or officers or any other person whom the Company or any of its
Subsidiaries has agreed to indemnify, as such; nor is there any reasonable basis
for any such Litigation that, individually or in the aggregate, could reasonably
be expected to have a Material Adverse Effect on the Company.

         4.       Representations and Warranties of the Janus. Janus represents
and warrants to the Company as follows:

         4.1      Authorization. All action on the part of Janus and, if
applicable, its officers, directors and shareholders necessary for the
authorization, execution, delivery and performance of this Agreement and the
Registration Rights Agreement and the consummation of the transactions
contemplated herein and therein has been taken. Each of this Agreement and the
Registration Rights Agreement constitutes the legal, valid and binding
obligation of Janus, enforceable against Janus in accordance with its terms,
except as such may be limited by bankruptcy, insolvency, reorganization or other
laws affecting creditors' rights generally. Janus has all requisite power to
enter into each of this Agreement and the Registration Rights Agreement and to
carry out and perform its obligations under the terms of this Agreement and the
Registration Rights Agreement.

         4.2      Purchase Entirely for Own Account, Etc. Janus is acquiring the


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Shares for its own account, and not with a view to, or for sale in connection
with, any distribution of the Shares in violation of the Securities Act. Except
as contemplated by this Agreement, Janus has no present agreement, undertaking,
arrangement, obligation or commitment providing for the disposition of the
Shares. Janus represents that is has not been organized, reorganized or
recapitalized specifically for the purpose of investing in the Shares. Janus
agrees not to assign, sell, pledge, transfer or otherwise dispose of or transfer
any Shares unless registered under the Securities Act and applicable state
securities laws, or an opinion is given by counsel satisfactory to the Company
that such registration is not required. The Company may affix a legend to any
certificates representing the Shares to the foregoing effect.

         4.3      Investor Status; Etc. Janus certifies and represents to the
Company that at the time Janus acquires any of the Shares, Janus will be an
"accredited investor" as defined in Rule 501 of Regulation D promulgated under
the Securities Act and an "institutional investor" within the meaning of Section
802.64(a) of the regulations adopted under of the HSR Act. Janus's financial
condition is such that it is able to bear the risk of holding the Shares for an
indefinite period of time and the risk of loss of its entire investment. Janus
has been afforded the opportunity to ask questions of and receive answers from
the management of the Company concerning this investment and has sufficient
knowledge and experience in investing in companies similar to the Company in
terms of the Company's stage of development so as to be able to evaluate the
risks and merits of its investment in the Company. The purchase of the Common
Stock by Janus is being made directly by it in the ordinary course of business
within the meaning of Section 802.64(b) of the regulations promulgated under of
the HSR Act.

         4.4      Shares Not Registered. Janus understands that the Shares have
not been registered under the Securities Act, by reason of their issuance by the
Company in a transaction exempt from the registration requirements of the
Securities Act, and that the Shares must continue to be held by Janus unless a
subsequent disposition thereof is registered under the Securities Act or is
exempt from such registration. Janus understands that the exemptions from
registration afforded by Rule 144 (the provisions of which are known to it)
promulgated under the Securities Act depend on the satisfaction of various
conditions, and that, if applicable, Rule 144 may afford the basis for sales
only in limited amounts.

         4.5      No Conflict. The execution and delivery of this Agreement and
the Registration Rights Agreement by Janus and the consummation of the
transactions contemplated hereby and thereby will not conflict with or result in
any violation of or default by Janus (with or without notice or lapse of time,
or both) under, or give rise to a right of termination, cancellation or
acceleration of any obligation or to a loss of a material benefit under (i) any
provision of the organizational documents of Janus or (ii) any agreement or
instrument, permit, franchise, license, judgment, order, statute, law,
ordinance, rule or regulations, applicable to Janus or its respective properties
or assets.

         4.6      Brokers. Janus has not retained, utilized or been represented
by any broker or finder in connection with the transactions contemplated by this
Agreement.


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         4.7      Consents. All consents, approvals, orders and authorizations
required on the part of Janus in connection with the execution, delivery or
performance of this Agreement and the consummation of the transactions
contemplated herein have been obtained and are effective as of the Closing Date.

         5.       Conditions Precedent.

         5.1.     Conditions to the Obligation of Janus to Consummate the
Closing. The obligation of Janus to consummate the Closing and to purchase and
pay for the Shares being purchased by it pursuant to this Agreement is subject
to the satisfaction of the following conditions precedent:

         (a)      The representations and warranties contained herein of the
Company shall be true and correct on and as of the Closing Date with the same
force and effect as though made on and as of the Closing Date (it being
understood and agreed by Janus that, in the case of any representation and
warranty of the Company contained herein (i) which is not hereinabove qualified
by application thereto of a materiality standard, such representation and
warranty need be true and correct only in all Material respects in order to
satisfy as to such representation or warranty the condition precedent set forth
in the foregoing provisions of this Section 5.1 (a) or (ii) which is made as of
a specific date, such representation and warranty need be true and correct only
as of such specific date in order to satisfy as to such representation and
warranty the condition precedent set forth in the foregoing provisions of this
Section 5.1(a)).

         (b)      The Registration Rights Agreement shall have been executed and
delivered by the Company.

         (c)      The Company shall have performed in all material respects all
obligations and conditions herein required to be performed or observed by the
Company on or prior to the Closing Date.

         (d)      No proceeding challenging this Agreement or the transactions
contemplated hereby, or seeking to prohibit, alter, prevent or materially delay
the Closing, shall have been instituted before any court, arbitrator or
governmental body, agency or official and shall be pending.

         (e)      The purchase of and payment for the Shares by Janus shall not
be prohibited by any Law or Order.

         (f)      All instruments and corporate proceedings in connection with
the transactions contemplated by this Agreement to be consummated at the Closing
shall be satisfactory in form and substance to Janus, and Janus shall have
received copies (executed or certified, as may be appropriate) of all documents
which Janus may have reasonably requested in connection with such transactions.

         5.2.     Conditions to the Obligation of the Company to Consummate the
Closing.


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The obligation of the Company to consummate the Closing and to issue and sell to
Janus the Shares to be purchased by it at the Closing is subject to the
satisfaction of the following conditions precedent:

         (a)      The representations and warranties contained herein of Janus
shall be true and correct on and as of the Closing Date with the same force and
effect as though made on and as of the Closing Date (it being understood and
agreed by the Company that, in the case of any representation and warranty of
Janus contained herein which is not hereinabove qualified by application thereto
of a materiality standard, such representation and warranty need be true and
correct only in all Material respects in order to satisfy as to such
representation or warranty the condition precedent set forth in the foregoing
provisions of this Section 5.2(a)).

         (b)      The Registration Rights Agreement shall have been executed and
delivered by Janus.

         (c)      Janus shall have performed in all material respects all
obligations and conditions herein required to be performed or observed by the
Janus on or prior to the Closing Date.

         (d)      No proceeding challenging this Agreement or the transactions
contemplated hereby, or seeking to prohibit, alter, prevent or materially delay
the Closing, shall have been instituted before any court, arbitrator or
governmental body, agency or official and shall be pending.

         (e)      The sale of the Shares by the Company shall not be prohibited
by any Law or Order.

         (f)      Janus shall have executed and delivered to the Company
confirmation of Janus's status as an "accredited investor" (as such term is
defined in Rule 501 promulgated under the Securities Act) and an "institutional
investor" (as such term is defined under 15 C.F.R. ss.802.64(a) of the HSR Act).

         (g)      Janus shall have purchased, in accordance with this Agreement,
15,000,000 shares of the Common Stock."

         (h)      All instruments and corporate proceedings in connection with
the transactions contemplated by this Agreement to be consummated at the Closing
shall be satisfactory in form and substance to the Company, and the Company
shall have received counterpart originals, or certified or other copies of all
documents, including without limitation records of corporate or other
proceedings, which it may have reasonably requested in connection therewith.

         6.       Shelf Registrations, Transfer, Legends

         6.1.     Shelf Registration. Subject to the Registration Rights
Agreement, the Company shall use its reasonable best efforts: (i) to file prior
to June 11, 2000 with the SEC a registration statement for a non-underwritten
offering to be made on a continuous


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basis pursuant to Rule 415 of the Securities Act relating to the Common Shares
underlying Janus's Shares (a "Shelf Registration") and (ii) to have the Shelf
Registration declared effective as soon as possible after July 26, 2000.

         6.2.     Securities Law Transfer Restrictions. Janus shall not sell,
assign, pledge, transfer or otherwise dispose or encumber any of the Shares
being purchased by it hereunder, except (i) pursuant to an effective
registration statement under the Securities Act or (ii) pursuant to an available
exemption from registration under the Securities Act and applicable state
securities laws and, if requested by the Company, upon delivery by Janus of an
opinion of counsel reasonably satisfactory to the Company to the effect that the
proposed transfer is exempt from registration under the Securities Act and
applicable state securities laws. Any transfer or purported transfer of the
Shares in violation of this Section 6.1 shall be voidable by the Company. The
Company shall not register any transfer of the Shares in violation of this
Section 6.1. The Company may, and may instruct any transfer agent for the
Company, to place such stop transfer orders as may be required on the transfer
books of the Company in order to ensure compliance with the provisions of this
Section 6.1.

         6.3.     Legends. Each certificate requesting any of the Shares shall
be endorsed with the legends set forth below, and Janus covenants that, except
to the extent such restrictions are waived by the Company, it shall not transfer
the shares represented by any such certificate without complying with the
restrictions on transfer described in this Agreement and the legends endorsed on
such certificate:

"THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933 AND MAY NOT BE OFFERED, SOLD,
ASSIGNED, PLEDGED TRANSFERRED OR OTHERWISE DISPOSED OF IN THE ABSENCE OF AN
EFFECTIVE REGISTRATION STATEMENT UNDER SAID ACT OR PURSUANT TO AN AVAILABLE
EXEMPTION FROM REGISTRATION UNDER SAID ACT AND, IF REQUESTED BY THE COMPANY,
UPON DELIVERY OF AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE COMPANY
THAT THE PROPOSED TRANSFER IS EXEMPT FROM SAID ACT."

         6.4.     Restrictions on Transfer. In addition, Janus hereby expressly
covenants and agrees that it shall not (i) offer, pledge, sell, contract to
sell, sell any option or contract to purchase, purchase any option or contract
to sell, grant any option, right or warrant to purchase, or otherwise transfer
or dispose of, directly or indirectly, any of the Shares issued pursuant to this
Agreement (the "Subject Stock") or any securities convertible into or
exercisable or exchangeable for the Subject Stock (including, without
limitation, shares of the Subject Stock or securities convertible into or
exercisable or exchangeable for the Subject Stock which may be deemed to be
beneficially owned by such holder in accordance with the rules and regulations
of the SEC) or (ii) enter into any swap or other arrangement that transfers all
or a portion of the economic consequences associated with the ownership of any
Subject Stock (regardless of whether any of the transactions described in clause
(i) or clause (ii) is to be settled by the delivery of Subject Stock, or such
other securities, in cash or otherwise (each action described herein is referred
to as a "Transfer"). Notwithstanding any provision of this Section 6.4 to the


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contrary and subject to compliance with the Securities Laws, Janus may Transfer
such Subject Stock to any Affiliate of Janus.

         7.       Miscellaneous Provisions.

         7.1      Public Statements or Releases. Janus shall not make, issue, or
release any announcement, whether to the public generally, or to any of its
suppliers or customers, with respect to this Agreement or the transactions
provided for herein, or make any statement or acknowledgment of the existence
of, or reveal the status of, this Agreement or the transactions provided for
herein, without the prior consent of the Company, which shall not be
unreasonably withheld or delayed, provided that nothing in this Section 7.1
shall prevent any of the parties hereto from making such public announcements as
it may consider necessary in order to satisfy its legal obligations, but to the
extent not inconsistent with such obligations, it shall provide the other
parties with an opportunity to review and comment on any proposed public
announcement before it is made.

         7.2      Further Assurances. Each party agrees to cooperate fully with
the other party and to execute such further instruments, documents and
agreements and to give such further written assurances, as may be reasonably
requested by the other party to better evidence and reflect the transactions
described herein and contemplated hereby, and to carry into effect the intents
and purposes of this Agreement.

         7.3      Rights Cumulative. Each and all of the various rights, powers
and remedies of the parties shall be considered to be cumulative with and in
addition to any other rights, powers and remedies which such parties may have at
law or in equity in the event of the breach of any of the terms of this
Agreement. The exercise or partial exercise of any right, power or remedy shall
neither constitute the exclusive election thereof nor the waiver of any other
right, power or remedy available to such party.

         7.4      Pronouns. All pronouns or any variation thereof shall be
deemed to refer to the masculine, feminine or neuter, singular or plural, as the
identity of the person, persons, entity or entities may require.


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<PAGE>   13

         7.5      Notices.

         (a)      Any notices, reports or other correspondence (hereinafter
collectively referred to as "correspondence") required or permitted to be given
hereunder shall be sent by postage prepaid first class mail, courier 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.

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

         Healtheon/WebMD Corporation
         400 the Lenox Building
         3399 Peachtree Road NE,
         Atlanta, Georgia  30326
         Attention:  Jack Dennison

         Copy to Counsel:    Nelson Mullins Riley & Scarborough, L.L.P.
                             Bank of America Corporate Center
                             100 N. Tryon Street
                             Charlotte, North Carolina  28202
                             Telecopy Number:  (704) 377-4814
                             Attention:  H. Bryan Ives III

         (c)      All correspondence to Janus shall be addressed as follows:

         Janus
         100 Fillmore Street
         Denver, Co 80206
         Attention:  Heidi J. Walter, Vice President and Assistant General
Counsel

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

         7.6      Captions. The captions and paragraph headings of this
Agreement are solely for the convenience of reference and shall not affect its
interpretation.

         7.7      Severability. Should any part or provision of this Agreement
be held unenforceable or in conflict with the applicable laws or regulations of
any jurisdiction, the invalid or unenforceable part or provisions shall be
replaced with a provision which accomplishes, to the extent possible, the
original business purpose of such part or provision in a valid and enforceable
manner, and the remainder of this Agreement shall remain binding upon the
parties hereto.

         7.8      Governing Law; Injunctive Relief.


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<PAGE>   14

         (a)      This Agreement shall be governed by and construed in
accordance with the internal and substantive laws of Delaware and without regard
to any conflicts of laws concepts which would apply the substantive law of some
other jurisdiction.

         (b)      Each of the parties hereto acknowledges and agrees that
damages will not be an adequate remedy for any material breach or violation of
this Agreement if such material breach or violation would cause immediate and
irreparable harm (an "Irreparable Breach"). Accordingly, in the event of a
threatened or ongoing Irreparable Breach, each party hereto shall be entitled to
seek, in any state or federal court in Delaware, equitable relief of a kind
appropriate in light of the nature of the ongoing or threatened Irreparable
Breach, which relief may include, without limitation, specific performance or
injunctive relief; provided, however, that if the party bringing such action is
unsuccessful in obtaining the relief sought, the moving party shall pay the
non-moving party's reasonable costs, including attorney's fees, incurred in
connection with defending such action. Such remedies shall not be the parties'
exclusive remedies, but shall be in addition to all other remedies provided in
this Agreement.

         7.9      Waiver. No waiver of any term, provision or condition of this
Agreement, whether by conduct or otherwise, in any one or more instances, shall
be deemed to be, or be construed as, a further or continuing waiver of any such
term, provision or condition or as a waiver of any other term, provision or
condition of this Agreement.

         7.10     Expenses. Each party will bear its own costs and expenses in
connection with this Agreement.

         7.11     Assignment. The rights and obligations of the parties hereto
shall inure to the benefit of and shall be binding upon the authorized
successors and permitted assigns of each party. Neither party may assign its
rights or obligations under this Agreement or designate another person (i) to
perform all or part of its obligations under this Agreement or (ii) to have all
or part of its rights and benefits under this Agreement, in each case without
the prior written consent of the other party. In the event of any assignment in
accordance with the terms of this Agreement, the assignee shall specifically
assume and be bound by the provisions of the Agreement by executing and agreeing
to an assumption agreement reasonably acceptable to the other party.

         7.12     Survival. The respective representations and warranties given
by the parties hereto, and the other covenants and agreements contained herein,
shall survive the Closing Date and the consummation of the transactions
contemplated herein for a period of 90 days, without regard to any investigation
made by any party.

         7.13     Entire Agreement. This Agreement constitutes the entire
agreement between the parties hereto respecting the subject matter hereof and
supersedes all prior agreements, negotiations, understandings, representations
and statements respecting the subject matter hereof, whether written or oral. No
modification, alteration, waiver or change in any of the terms of this Agreement
shall be valid or binding upon the parties hereto unless made in writing and
duly executed by parties.


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                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK.]


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This Stock Purchase Agreement is hereby executed as of the date first above
written.


                                            COMPANY:

                                            HEALTHEON/WEBMD CORPORATION


                                            By: /s/
                                               ---------------------------------
                                                 Its:
                                                     ---------------------------


                                            JANUS CAPITAL CORPORATION


                                            By: /s/
                                               ---------------------------------
                                                 Its:
                                                     ---------------------------


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