Document:

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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

                                       11
<PAGE>   12

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.

                                       12
<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.

                                       13
<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.

                                       14
<PAGE>   15

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK.]

                                       15
<PAGE>   16

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:
                                                     ---------------------------

                                       16<PAGE>   1
                                                                   EXHIBIT 10.11

                           HEALTHEON/WEBMD CORPORATION
                          REGISTRATION RIGHTS AGREEMENT

         This Registration Rights Agreement (the "AGREEMENT") is made and
entered into as of the 26th day of January, 2000 among Healtheon/WebMD
Corporation, a Delaware corporation (the "COMPANY"), and the party set forth on
signature pages hereto (the "PURCHASER").

                                R E C I T A L S:

         A.       The Purchaser has purchased 15,000,000 shares of the Company's
Common Stock, par value $0.0001 per share (the "COMMON STOCK") pursuant to a
Stock Purchase Agreement dated as of the date hereof, (the "PURCHASE AGREEMENT")
between the Company and the Purchaser.

         B.       The Company and the Purchaser desire to set forth the
registration rights to be granted by the Company to the Purchaser.

         NOW, THEREFORE, in consideration of the mutual promises,
representations, warranties, covenants, and conditions set forth herein and in
the Purchase Agreement, the parties mutually agree as follows:

                               A G R E E M E N T:

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

         "Certificate of Incorporation" means the Amended and Restated
Certificate of Incorporation of the Company as filed with the Secretary of State
of the State of Delaware, as amended from time to time.

         "Commission" shall mean the Securities and Exchange Commission or any
other federal agency at the time administering the Securities Act.

         "Common Stock" shall mean the common stock, par value $0.0001 per
share, of the Company and any and all shares of capital stock or other equity
securities of: (i) the Company which are added to or exchanged or substituted
for the Common Stock by reason of the declaration of any stock dividend or stock
split, the issuance of any distribution or the reclassification, readjustment,
recapitalization or other such modification of the capital structure of the
Company; and (ii) any other corporation, now or hereafter organized under the
laws of any state or other governmental authority, with which the Company is
merged, which results from any consolidation or reorganization to which the
Company is a party, or to which is sold all or substantially all of the shares
or assets of the Company, if immediately after such merger, consolidation,
reorganization or sale, the Company or any Stockholders of the Company own
equity securities having in the aggregate more than fifty percent (50%) of the
total voting power of such other corporation.

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

         "Family Member" shall mean (a) with respect to any individual, such
individual's spouse, any descendants (whether natural, adopted or in the process
of adoption), any trust all of the beneficial interests of which are owned by
any of such individuals or by any of such individuals together with any
<PAGE>   2

organization described in Code Section 501(c)(3), the estate of any such
individual, and any corporation, association, partnership or limited liability
company all of the equity interests of which are owned by those above described
individuals, trusts or organizations and (b) with respect to any trust, the
owners of the beneficial interests of such trust.

         "Form S-3" means such form under the Securities Act as in effect on the
date hereof or any registration form under the Securities Act subsequently
adopted by the Commission which permits inclusion or incorporation of
substantial information by reference to other documents filed by the Company
with the Commission.

         "Holder" shall mean the Purchaser or any of such Holder's respective
successors and assigns who acquire rights in accordance with this Agreement with
respect to the Registrable Securities directly or indirectly from such Holder.

         "Initiating Holders" shall mean any Holder or Holders of not less than
50% of the then outstanding Registrable Securities.

         The terms "register", "registered" and "registration" refer to a
registration effected by preparing and filing a registration statement in
compliance with the Securities Act, and the declaration or ordering of the
effectiveness of such registration statement.

         "Registrable Securities" means shares of Common Stock issued pursuant
to the Purchase Agreement, excluding in all cases, however (including exclusion
from the calculation of the number of outstanding Registrable Securities), any
Registrable Securities sold by a person in a transaction (i) pursuant to a
registration statement under Section 2, 3 or 4 hereof or (ii) pursuant to Rule
144 (or any successor provision) of the Securities Act.

         "Securities Act" shall mean the Securities Act of 1933, as amended, or
any similar federal statute promulgated in replacement thereof, and the rules
and regulations of the Commission thereunder, all as the same shall be in effect
at the time.

         2.       Demand Registration. In case the Company shall receive from
Initiating Holders a written request that the Company effect a registration with
respect to at least 2,000,000 shares of Common Stock that constitute Registrable
Securities (as adjusted for stock splits, stock dividends, recapitalizations and
similar events) the Company will:

         (a)      promptly give written notice of the proposed registration to
all other Holders so they may have an opportunity to consider joining in such
registration, which they may do (subject to the terms and provisions of this
Agreement) at their election within ten (10) days after receipt of the notice of
the proposed registration by the Company; and

         (b)      as soon as practicable, use its reasonable best efforts to
effect such registration (including, without limitation, the execution of an
undertaking to file post-effective amendments, appropriate qualification under
applicable blue sky or other state securities laws and appropriate compliance
with applicable regulations issued under the Securities Act) as may be so
requested and as would permit or facilitate the sale and distribution of all or
such portion of such Registrable Securities as are specified in such request,
together with all or such portion of the Registrable Securities of any

                                       2
<PAGE>   3
Holder or Holders joining in such request as are specified in a written request
given within ten (10) days after receipt of notice from the Company pursuant to
Section 2(a); provided that the Company shall not be obligated to take any
action to effect any such registration, qualification or compliance pursuant to
this Section 2:

                  (i)      In any particular jurisdiction in which the Company
would be required to execute a general consent to service of process in
effecting such registration, qualification or compliance unless the Company is
already subject to service in such jurisdiction and except as may be required by
the Securities Act;

                  (ii)     Prior to July 26, 2000;

                  (iii)    Within the one hundred twenty (120) day period
immediately following the effective date of a registration statement pertaining
to a firm commitment underwritten public offering of Common Stock for the
account of a shareholder (including Purchaser) of the Company who has exercised
a demand right to register shares of Common Stock (other than a registration
relating solely to a Commission Rule 145 transaction, a registration relating
solely to employee benefit plans, or a registration statement on Form S-3 (or
any similar short-form registration statement));

                  (iv)     Within the sixty (60) day period immediately
following the effective date of a registration statement on Form S-3 (or any
similar short-form registration statement) pertaining to a firm commitment
underwritten public offering of Common Stock for the account of another
shareholder of the Company who has exercised a demand right to register shares
of Common Stock (other than a registration relating solely to a Commission Rule
145 transaction or a registration relating solely to employee benefit plans); or

                  (v)      After the Company has effected three (3)
registrations pursuant to this Section 2 and such registrations have been
declared or ordered effective and have remained effective for a period of at
least ninety (90) consecutive days.

         Subject to the foregoing clauses (i) through (v), the Company shall
file a registration statement covering the Registrable Securities so requested
to be registered as soon as practicable after receipt of the request of the
Initiating Holders. The Initiating Holders may, at any time prior to the
effective date of the registration statement relating to such registration,
revoke such request, without liability (except as set forth in Section 6 hereof)
to the Initiating Holders or any other Holders of Registrable Securities
requested to be registered pursuant to Section 2(a) hereof, by providing a
written notice to the Company revoking such request.

         Notwithstanding the above, the Company shall not be obligated to
effect, or to take any action to effect, any registration pursuant to this
Section 2 during the period starting with the date ninety (90) days prior to the
Company's good faith estimate of the date of filing of (or in the case of any
registration on Form S-3, forty-five (45) days prior), and ending on a date one
hundred twenty (120) days after the effective date of (or in the case of any
registration on Form S-3, ninety (90) days after), a Company-initiated
registration statement in connection with a bona fide firm commitment
underwritten registration for securities to be offered for the Company's own
account (the "Intended Registration"); provided that the Company is actively
employing in good faith all reasonable efforts to cause the Intended
Registration to become effective and provided further that the Company gives
notice to all Holders upon commencement of such period. The Holders shall be
entitled to exercise their rights pursuant to Section 4 hereof with respect to
an Intended Registration. An Intended Registration shall not be deemed to be a
demand registration of the Holders pursuant to this Section 2.

                                       3
<PAGE>   4
         (c)      Underwriting. If the Holders propose an underwritten offering,
the sale of Registrable Securities pursuant to this Section 2 must be made by
means of a firm commitment underwriting through nationally recognized
underwriters who are acceptable to the Company and the holders of a majority of
the Registrable Securities that are proposed to be distributed through such
underwriting. The right of any Holder to registration pursuant to this Section 2
shall be conditioned upon such Holder's participation in such underwriting and
the inclusion of such Holder's Registrable Securities in the underwriting to the
extent requested by such Holder (unless mutually otherwise agreed by a majority
in interest of the Holders and such Holder) to the extent provided herein.

         The Company and all Holders proposing to distribute Registrable
Securities through such underwriting shall enter into an underwriting agreement
in customary form with the underwriter or underwriters selected for such
underwriting. Notwithstanding any other provision of this Section 2(c), if the
underwriter determines that in its good faith view marketing factors require a
limitation of the number of shares to be underwritten and so advises the
Initiating Holders in writing, then the Initiating Holders shall so advise the
Company and all Holders (except those Holders who have indicated to the Company
their decision not to distribute any of their Registrable Securities through
such underwriting) and the number of Registrable Securities that may be included
in the registration and underwriting shall be allocated first to the Holders on
a pro rata basis according to the number of Registrable Securities requested to
be included by the Holders; second to the Company; and third to other
shareholders of the Company who have requested to sell in the registration. No
Registrable Securities excluded from the underwriting by reason of the
underwriter's marketing limitation shall be included in such registration. If at
least eighty percent (80%) of the Registrable Securities requested to be
registered by the Initiating Holders are not included in such registration, then
the Initiating Holders may request that the Company effect an additional
registration under the Securities Act of all or part of the Initiating Holders'
Registrable Securities in accordance with the provisions of this Section 2, and
the Company shall effect such additional registration.

         If any Holder disapproves of the terms of the underwriting, such person
may elect to withdraw therefrom by written notice to the Company, the
underwriter and the Initiating Holders. The Registrable Securities and/or other
securities so withdrawn from such underwriting shall also be withdrawn from such
registration; provided, however, that, if by the withdrawal of such Registrable
Securities a greater number of Registrable Securities held by other Holders may
be included in such registration (up to the maximum of any limitation imposed by
the underwriters), then the Company shall offer to all Holders who have included
Registrable Securities in the registration the right to include additional
Registrable Securities in the same proportion used above in determining the
underwriter limitation.

         If the underwriter has not limited the number of Registrable Securities
to be underwritten, the Company may include securities for its own account or
the account of others in such registration if the underwriter so agrees and if
the number of Registrable Securities which would otherwise have been included in
such registration and underwriting will not thereby be limited.

                                       4
<PAGE>   5
         (d)      If the Company shall furnish to the Initiating Holders a
certificate signed by the President of the Company stating that, in the good
faith judgment of the Board of Directors of the Company, it would (because of
the existence of, or in anticipation of, any acquisition, financing activity, or
other transaction involving the Company, or the unavailability for reasons
beyond the Company's control of any required financial statements, disclosure of
information which is in its best interest not to publicly disclose, or any other
event or condition of similar significance to the Company) be seriously
detrimental to the Company and its shareholders for such registration statement
to be filed on or before the date filing would be required and it is therefore
essential to defer the filing of such registration statement, then the Company
may direct that such request for registration be delayed for a period not in
excess of ninety (90) days, such right to delay a request to be exercised by the
Company not more than twice in any twelve (12) month period.

         (e)      Effective Registration Statement. A demand registration
requested pursuant to this Section 2 shall not be deemed to have been effected
unless the registration statement relating thereto (i) has become effective
under the Securities Act and any of the Registrable Securities of the Initiating
Holders included in such registration have actually been sold thereunder, and
(ii) has remained effective for a period of at least ninety (90) days (or such
shorter period in which all Registrable Securities included in such registration
have actually been sold thereunder).

           3. S-3 Registration. In case the Company shall receive from any
Holder or Holders a written request or requests that the Company effect a
registration on Form S-3 and any related qualification or compliance with
respect to all or a part of the Registrable Securities owned by such Holder or
Holders, the Company will:

         (a)      promptly give written notice of the proposed registration,
and any related qualification or compliance, to all other Holders; and

         (b)      as soon as practicable, and in any event within 30 days of the
receipt of such notice, file a registration statement on Form S-3 and effect all
other qualifications and compliances as may be so requested and as would permit
or facilitate the sale, distribution, transfer or hedging (through market
transactions using brokers, in a firm commitment underwriting, in negotiated
transactions or otherwise) of all or such portion of such Holder's or Holders'
Registrable Securities as are specified in such request, together with all or
such portion of the Registrable Securities of any other Holder or Holders
joining in such request as are specified in a written request given within 15
days after receipt of such written notice from the Company; provided, that the
Company shall not be obligated to effect any such registration, qualification or
compliance pursuant to this Section 3:

                  (i)      if Form S-3 is not available for such offering by the
Holders;

                  (ii)     if the Holders, together with the holders of any
other securities of the Company entitled to inclusion in such registration,
propose to register Registrable Securities and such other securities (if any) at
an aggregate price to the public (net of any underwriters' discounts or
commissions) of less than $10 million;

                  (iii)    if the Company has, within the twelve (12) month
period preceding the date of such request, already effected three (3)
registrations for the Holders pursuant to this Section 1.3; or

                                       5
<PAGE>   6
                  (iv)     in any particular jurisdiction in which the Company
would be required to qualify to do business or to execute a general consent to
service of process in effecting such registration, qualification or compliance;
or

                  (v)      Prior to July 26, 2000.

         (c)      Subject to the foregoing, the Company shall file a
registration statement covering the Registrable Securities and other securities
so requested to be registered as soon as practicable after receipt of the
request or requests of the Holders and shall keep it continuously effective
until such Registrable Securities have been sold pursuant thereto.

         (d)      Notwithstanding the other provisions of this Section 3, the
Company shall have the right to delay the filing of any registration statement
on Form S-3 (an "S-3 Registration") otherwise required to be prepared and filed
by the Company pursuant to this Section 3, or to suspend the use of any S-3
Registration, for a period not in excess of 60 days (a "S-3 BLACKOUT PERIOD") if
the Company, in the good faith judgment of its Board of Directors, determines
(because of the existence of, or in anticipation of, any acquisition, financing
activity, or other transaction involving the Company, or the unavailability for
reasons beyond the Company's control of any required financial statements,
disclosure of information which is in its best interest not to publicly
disclose, or any other event or condition of similar significance to the
Company) that the registration and distribution of the Registrable Securities to
be covered by such S-3 Registration would be seriously detrimental to the
Company and its shareholders, provided that the S-3 Blackout Period shall
earlier terminate on the second business day following the completion or
abandonment of the relevant financing, acquisition or other transaction or upon
public disclosure by the Company or public admission by the Company of such
material nonpublic information or such time as such material nonpublic
information shall be publicly disclosed; and provided, further, that the Company
shall furnish to the Holders a certificate of an executive officer of the
Company to the effect that an event permitting a S-3 Blackout Period has
occurred (and no other reason need be given). The Company will promptly give the
Holders written notice of such determination and an approximation of the period
of the anticipated delay; provided, however, that the aggregate number of days
included in all S-3 Blackout Periods during any consecutive 12 months shall not
exceed 180 days. Each Holder agrees to cease all disposition efforts under such
S-3 Registration with respect to Registrable Securities held by such Holder
immediately upon receipt of notice of the beginning of any S-3 Blackout Period.
The Company shall provide written notice to the Holders of the end of each S-3
Blackout Period.

         4.       Piggyback Registration.

         (a)      If the Company shall determine to register for sale for cash
any of its Common Stock, for its own account or for the account of others (other
than the Holders), other than a registration relating solely to employee benefit
plans or securities issued or issuable to employees, consultants (to the extent
the securities owned or to be owned by such consultants could be registered on
Form S-8) or any of their Family Members (including a registration on Form S-8),
or a registration relating solely to a Commission Rule 145 transaction, a
registration on Form S-4 in connection with a merger, acquisition, divestiture,
reorganization or similar event, the Company promptly will give to each Holder
written notice thereof and shall use its reasonable best efforts to include in
such registration (and any related qualification under blue sky laws or other
compliance), and in any underwriting involved therein, all the Registrable
Securities specified in a written request or requests, made within ten (10) days
after receipt of such written notice from the Company, by any Holder or Holders.
However, the Company may, without the consent of the Holders, withdraw such
registration statement prior to its

                                       6
<PAGE>   7
becoming effective if the Company has abandoned its proposal to register the
securities proposed to be registered thereby.

         (b)      Underwriting. If the registration of which the Company gives
notice is for a registered public offering involving an underwriting, the
Company shall so advise the Holders as a part of the written notice given
pursuant to Section 4(a). In such event the right of any Holder to registration
pursuant to Section 4(a) shall be conditioned upon such Holder's participation
in such underwriting and the inclusion of such Holder's Registrable Securities
in the underwriting to the extent provided herein. All Holders proposing to
distribute their securities through such underwriting shall (together with the
Company and any other shareholders of the Company distributing their securities
through such underwriting) enter into an underwriting agreement in customary
form with the underwriter or underwriters selected for such underwriting by the
Company. Notwithstanding any other provision of this Section 4(b), if the
underwriter or the Company determines that marketing factors require a
limitation of the number of shares to be underwritten, the underwriter may
exclude some or all Registrable Securities from such registration and
underwriting. The Company shall so advise all Holders (except those Holders who
have indicated to the Company their decision not to distribute any of their
Registrable Securities through such underwriting), and the number of shares of
Registrable Securities that may be included in the registration and
underwriting, if any, shall be allocated among such Holders as follows:

                  (i)      In the event of a piggyback registration pursuant to
Section 4(a) that is initiated by the Company, then the number of shares that
may be included in the registration and underwriting shall be allocated first to
the Company and then to all selling shareholders, including the Holders, who
have requested to sell in the registration on a pro rata basis according to the
number of shares requested to be included; provided, however, that no allocation
pursuant to this Section 4(b) shall have the effect of reducing the Shares sold
by Holders to less than 20% of the proposed offering; and

                  (ii)     In the event of a piggyback registration pursuant to
Section 4(a) that is initiated by the exercise of demand registration rights by
a shareholder or shareholders of the Company (other than the Holders), then the
number of shares that may be included in the registration and underwriting shall
be allocated first to such selling shareholders who exercised such demand and
then to all selling shareholders, including the Holders, who have requested to
sell in the registration, on a pro rata basis according to the number of shares
requested to be included.

         (c)      No Registrable Securities excluded from the underwriting by
reason of the underwriter's marketing limitation shall be included in such
registration. If any Holder disapproves of the terms of any such underwriting,
such person may elect to withdraw therefrom by written notice to the Company and
the underwriter. The Registrable Securities and/or other securities so withdrawn
from such underwriting shall also be withdrawn from such registration; provided,
however, that, if by the withdrawal of such Registrable Securities a greater
number of Registrable Securities held by other Holders may be included in such
registration (up to the maximum of any limitation imposed by the underwriters),
then the Company shall offer to all Holders who have included Registrable
Securities in the registration the right to include additional Registrable
Securities pursuant to the terms and limitations set forth herein in the same
proportion used above in determining the underwriter limitation.

         5.       Registration Procedures. In the case of each registration,
qualification or compliance effected by the Company pursuant to Section 2, 3 or
4 hereof, the Company will keep each Holder advised in writing as to the
initiation of each registration, qualification and compliance and as to the
completion thereof. At its expense, the Company will use its reasonable best
efforts to:

                                       7
<PAGE>   8

         (a)      prepare and file with the Commission within ninety (90) days
(or in the case of any registration on Form S-3, thirty (30) days) after receipt
of a request for registration with respect to such Registrable Securities, a
registration statement on any form for which the Company then qualifies or which
counsel for the Company shall deem appropriate, subject to Section 2 hereof, and
which form shall be available for the sale of the Registrable Securities in
accordance with the intended method(s) of distribution thereof, and use its best
efforts to cause such registration statement to become and remain effective;
provided that before filing with the Commission a registration statement or
prospectus or any amendments or supplements thereto, including documents
incorporated by reference after the initial filing of any registration
statement, the Company shall (i) furnish to the underwriters, if any, and to one
(1) counsel selected by the Holders of a majority of the Registrable Securities
covered by such registration statement copies of all such documents proposed to
be filed, which documents shall be subject to the review of the underwriters and
such counsel, and (ii) notify each Holder of Registrable Securities covered by
such registration statement of any stop order issued or threatened by the
Commission and take all reasonable actions required to prevent the entry of such
stop order or to remove it if entered;

         (b)      prepare and file with the Commission such amendments and
supplements to such registration statement and the prospectus used in connection
therewith as may be necessary to keep such registration statement effective for
a period of not less than ninety (90) days or such shorter period which shall
terminate when all Registrable Securities covered by such registration statement
have been sold (but not before the expiration of the 90-day period referred to
in Section 4(3) of the Securities Act and Rule 174, or any successor thereto,
thereunder, if applicable), and comply with the provisions of the Securities Act
with respect to the disposition of all securities covered by such registration
statement during such period in accordance with the intended method(s) of
disposition by the sellers thereof set forth in such registration statement;

         (c)      furnish, without charge, to each Holder and each underwriter,
if any, of Registrable Securities covered by such registration statement one (1)
signed copy of such registration statement, each amendment and supplement
thereto (including one (1) conformed copy to each Holder and one (1) signed copy
to each managing underwriter and in each case including all exhibits thereto),
and such number of copies of the prospectus included in such registration
statement (including each preliminary prospectus and any other prospectus filed
under Rule 424 under the Securities Act) as such Holders may request, in
conformity with the requirements of the Securities Act, and such other documents
as such Holder may reasonably request in order to facilitate the disposition of
the Registrable Securities owned by such Holder, but only while the Company
shall be required under the provisions hereof to cause the registration
statement to remain effective;

         (d)      use its best efforts to register or qualify such Registrable
Securities under such other applicable securities or blue sky laws of such
jurisdictions as any Holder, and underwriter, if any, of Registrable Securities
covered by such registration statement reasonably requests as may be necessary
for the marketability of the Registrable Securities (such request to be made by
the time the applicable registration statement is deemed effective by the
Commission) and do any and all other acts and things which may be reasonably
necessary or advisable to enable such Holder and each underwriter, if any, to
consummate the disposition in such jurisdictions of the Registrable Securities
owned by such Holder; provided that the Company shall not be required to (i)
qualify generally to do business in any jurisdiction where it would not
otherwise be required to qualify but for this paragraph (d), (ii) subject itself
to taxation in any such jurisdiction, or (iii) consent to general service of
process in any such jurisdiction;

                                       8
<PAGE>   9
         (e)      use its best efforts to cause the Registrable Securities
covered by such registration statement to be registered with or approved by such
other governmental agencies or authorities as may be necessary by virtue of the
business and operations of the Company to enable the Holder or Holders thereof
to consummate the disposition of such Registrable Securities;

         (f)      immediately notify the managing underwriter, if any, and each
Holder of such Registrable Securities at any time when a prospectus relating
thereto is required to be delivered under the Securities Act of the happening of
any event which comes to the Company's attention if as a result of such event
the prospectus included in such registration statement contains an untrue
statement of a material fact or omits to state any material fact required to be
stated therein or necessary to make the statements therein not misleading and
the Company shall promptly prepare and furnish to such Holder a supplement or
amendment to such prospectus so that, as thereafter delivered to the purchasers
of such Registrable Securities, such prospectus shall not contain an untrue
statement of a material fact or omit to state any material fact required to be
stated therein or necessary to make the statements therein not misleading,
unless suspension of the use of such prospectus otherwise is authorized herein
or in the event of a S-3 Blackout Period, in which case no supplement or
amendment need be furnished;

         (g)      use its best efforts to cause all such Registrable Securities
covered by the registration statement to be listed on the Nasdaq Stock Market or
the national securities exchange on which  similar securities issued by the
Company are then listed, and enter into such customary agreements including a
listing application and indemnification agreement in customary form (provided
that the applicable listing requirements are satisfied), and to provide a
transfer agent and registrar for such Registrable Securities covered by such
registration statement no later than the effective date of such registration
statement;

         (h)      enter into such customary agreements (including an
underwriting agreement in customary form) and take all such other actions as the
Initiating Holders or the underwriters retained by such Holders, if any,
reasonably request in order to expedite or facilitate the disposition of such
Registrable Securities, including customary indemnification;

         (i)      make available for inspection during normal business hours by
any Holder of Registrable Securities covered by such registration statement, any
underwriter participating in any disposition pursuant to such registration
statement, and any attorney, accountant or other agent retained by any such
Holder or underwriter (collectively, the "Inspectors"), all financial and other
records, pertinent corporate documents and properties of the Company and its
subsidiaries (collectively, "Records"), if any, as shall be reasonably necessary
to enable them to exercise their due diligence responsibility, and cause the
Company's and its subsidiaries' officers, directors and employees to supply all
information and respond to all inquiries reasonably requested by any such
Inspector in connection with such registration statement. Notwithstanding the
foregoing, the Company shall have no obligation to disclose any Records to the
Inspectors in the event the Company determines that such disclosure is
reasonably likely to have an adverse effect on the Company's ability to assert
the existence of an attorney-client privilege with respect thereto;

         (j)      in the event that any contemplated public offering is
underwritten, use its best efforts to obtain a "comfort" letter from the
Company's independent public accountants in customary form and covering such
matters of the type customarily covered by "comfort" letters as the Holders of a
majority (by number of shares) of the Registrable Securities being sold
reasonably request, and provided that such request is reasonable in the
underwriter's point of view;

                                       9
<PAGE>   10
         (k)      use its best efforts to obtain an obtain an opinion of counsel
from the Company's counsel in customary form and covering such matters of the
type customarily covered in opinions of counsel in connection with such
transactions;

         (l)      comply, and continue to comply during the period that such
registration statement is effective under the Securities Act, in all material
respects with the Securities Act and the Securities Exchange Act of 1934 and
with all applicable rules and regulations of the Commission with respect to the
disposition of all securities covered by such registration statement, and make
available to its security holders, as soon as reasonably practicable, an
earnings statement covering the period of at least twelve (12) months, but not
more than eighteen (18) months, beginning with the first full calendar month
after the effective date of such registration statement, which earnings
statement shall satisfy the provisions of Section 11(a) of the Securities Act,
and not file any amendment or supplement to such registration statement or
prospectus to which Holder shall have reasonably objected on the grounds that
such amendment or supplement does not comply in all material respects with the
requirements of the Securities Act, having been furnished with a copy thereof at
least five (5) business days prior to the filing thereof; and

         (m)      in the event the offering is underwritten, develop a
presentation reasonably acceptable to the underwriters to facilitate the
offering and to make its chief executive officer and chief financial officer
available for participation in such meetings and presentations (e.g., road show
for the offering) at such locations (including Europe) as the underwriter
reasonably requests.

Each Holder of Registrable Securities agrees that, upon receipt of any notice
from the Company of the happening of any event of the kind described in Section
5(f) hereof or of the commencement of an S-3 Blackout Period, such Holder shall
discontinue disposition of Registrable Securities pursuant to the registration
statement covering such Registrable Securities until such Holder's receipt of
the copies of the supplemented or amended prospectus contemplated by Section
5(f) hereof or notice of the end of the S-3 Blackout Period, and, if so directed
by the Company, such Holder shall deliver to the Company (at the Company's
expense) all copies (including, without limitation, any and all drafts), other
than permanent file copies, then in such Holder's possession, of the prospectus
covering such Registrable Securities current at the time of receipt of such
notice. In the event the Company shall give any such notice, the period
mentioned in Section 5(b) hereof shall be extended by the greater of (i) ten
(10) business days or (ii) the number of days during the period from and
including the date of the giving of such notice pursuant to Section 5(f) hereof
to and including the date when each Holder of Registrable Securities covered by
such registration statement shall have received the copies of the supplemented
or amended prospectus contemplated by Section 5(f) hereof.

         6.       Rule 144. Notwithstanding anything to the contrary contained
herein, no Holder shall have rights to a registration under Section 2, 3 or 4
hereof after the time that such Holder could sell, within ninety (90) days, all
of its Registrable Securities pursuant to Rule 144(e) promulgated under the
Securities Act or any successor rule thereto; provided that the Company hereby
agrees to take the following actions to ensure the availability of Rule 144 to
each such Holder (or such similar actions as shall be required under any
successor rule thereto):

         (a)      make and keep public information available as those terms are
understood and defined in Rule 144;

         (b)      use its best efforts to file with the Commission in a timely
manner all reports and other documents required of the Company under the
Securities Act and the Exchange Act; and

                                       10
<PAGE>   11

         (c)      so long as any Holder owns any Registrable Securities, furnish
to a Holder upon request, a written statement by the Company as to its
compliance with the reporting requirements of Rule 144 (at any time from and
after ninety (90) days following the effective date of the registration
statement relating to an Initial Public Offering), and of the Securities Act and
the Exchange Act (at any time after it has become subject to such reporting
requirements), a copy of the most recent annual or quarterly report of the
Company, and such other reports and documents so filed as the Holder may
reasonably request.

         7.       Registration Expenses. The Company shall pay all expenses in
connection with any registration, including, without limitation, all
registration, filing and NASD fees, printing expenses, all fees and expenses of
complying with securities or blue sky laws, the fees and disbursements of one
counsel for the Holders and the fees and disbursements of counsel for the
Company and of its independent accountants; provided that, in any registration,
each party shall pay for its own underwriting discounts and commissions and
transfer taxes. The Company shall not, however, be required to pay for expenses
of any registration proceeding begun pursuant to Section 2, 3 or 4 hereof, the
request of which has been subsequently withdrawn by the Initiating Holders
(unless the withdrawal is based upon material adverse information concerning the
Company of which the Initiating Holders were unaware at the time of such
request), in which case such expenses shall be borne by the Holders whose
securities were to be included in the registration in proportion to the number
of shares for which such registration was requested.

         8.       Assignment of Rights. Any Holder may assign its rights under
this Agreement to any party acquiring 2,400,000 shares or more of Registrable
Securities; provided, however, that a Holder may assign its rights under this
Agreement without such restrictions to a transferee or assignee that controls,
is controlled by or is under common control with such Holder.

         9.       Information by Holder. The Holder or Holders of Registrable
Securities included in any registration shall furnish to the Company such
information regarding such Holder or Holders and the distribution proposed by
such Holder or Holders as the Company may request in writing.

         10.      "Market Stand-off" Agreement. Each Holder agrees not to sell
or otherwise transfer or dispose of any Common Stock (or other securities) of
the Company held by it until July 26, 2000, or during such period of time
following the effective date of an underwritten public offering of the Company's
securities as the underwriters in such underwritten offering deem appropriate;
provided, however, that no such market stand off agreement shall be required of
any Holder unless the executive officers, directors and greater than 10%
stockholders of the Company enter into similar agreements; provided, however,
that in no event shall such period be more than 90 days. The Company may impose
stop-transfer instructions with respect to the shares (or securities) subject to
the foregoing restriction until the end of such period.

         11.      Indemnification.

         (a)      In the event of the offer and sale of Registrable Securities
held by Holders under the 1933 Act, the Company shall, and hereby does,
indemnify and hold harmless, to the fullest extent permitted by law, each
Holder, its directors, officers, partners, each other person who participates as
an underwriter in the offering or sale of such securities, and each other
Person, if any, who controls or is under common control with such Holder or any
such underwriter within the meaning of Section 15 of the 1933 Act, against any
losses, claims, damages or liabilities, joint or several, and expenses to which
the Holder or any such director, officer, partner or underwriter or controlling
person may become

                                       11
<PAGE>   12
subject under the 1933 Act or otherwise, insofar as such losses, claims,
damages, liabilities or expenses (or actions or proceedings, whether commenced
or threatened, in respect thereof) arise out of or are based upon any untrue
statement or alleged untrue statement of any material fact contained in any
registration statement under which such shares were registered under the 1933
Act, any preliminary prospectus, final prospectus or summary prospectus
contained therein, or any amendment or supplement thereto, or any omission or
alleged omission to state therein a material fact required to be stated therein
or necessary to make the statements therein in light of the circumstances in
which they were made not misleading or any violation by the Company of any
federal, state or common law rule or regulation applicable to the Company and
relating to action required of or inaction by the Company in connection with any
such registration, and the Company shall reimburse the Holder, and each such
director, officer, partner, underwriter and controlling person for any legal or
any other expenses reasonably incurred by them in connection with investigating,
defending or settling any such loss, claim, damage, liability, action or
proceeding; provided that the Company shall not be liable in any such case to
the extent that any such loss, claim, damage, liability (or action or proceeding
in respect thereof) or expense arises out of or is based upon an untrue
statement or alleged untrue statement in or omission or alleged omission from
such registration statement, any such preliminary prospectus, final prospectus,
summary prospectus, amendment or supplement in reliance upon and in conformity
with written information furnished to the Company through an instrument duly
executed by or on behalf of such Holder specifically stating that it is for use
in the preparation thereof. Such indemnity shall remain in full force and effect
regardless of any investigation made by or on behalf of the Holders, or any such
director, officer, partner, underwriter or controlling person and shall survive
the transfer of such shares by the Holder.

         (b)      The Company may require, as a condition to including any
Registrable Securities to be offered by a Holder in any registration statement
filed pursuant to this Agreement, that the Company shall have received an
agreement from such Holder to be bound by the terms of this Section 11,
including an undertaking reasonably satisfactory to it from such Holder, to
indemnify and hold the Company, its directors and officers and each other
Person, if any, who controls the Company within the meaning of Section 15 of the
1933 Act, against any losses, claims, damages or liabilities, joint or several,
to which the Company or any such director or officer or controlling person may
become subject under the 1933 Act or otherwise, insofar as such losses, claims,
damages or liabilities (or actions or proceedings, whether commenced or
threatened, in respect thereof) arise out of or are based upon any untrue
statement or alleged untrue statement in or omission or alleged omission from
such registration statement, any preliminary prospectus, final prospectus or
summary prospectus contained therein, or any amendment or supplement thereto, if
such statement or alleged statement or omission or alleged omission was made in
reliance upon and in conformity with written information about such Holder as a
Holder of the Company furnished to the Company through an instrument duly
executed by such Holder specifically stating that it is for use in the
preparation of such registration statement, preliminary prospectus, final
prospectus, summary prospectus, amendment or supplement; provided, however, that
such indemnity agreement found in this Section 11(b) shall in no event exceed
the gross proceeds from the offering received by such Holder. Such indemnity
shall remain in full force and effect, regardless of any investigation made by
or on behalf of the Company or any such director, officer or controlling person
and shall survive the transfer by any Holder of such shares.

         (c)      Promptly after receipt by an indemnified party of notice of
the commencement of any action or proceeding involving a claim referred to in
Section 11(a) or (b) hereof (including any governmental action), such
indemnified party shall, if a claim in respect thereof is to be made against an
indemnifying party, give written notice to the indemnifying party of the
commencement of such action; provided that the failure of any indemnified party
to give notice as provided herein shall not relieve the indemnifying party of
its obligations under Section 11(a) or (b) hereof, except to the extent

                                       12
<PAGE>   13
that the indemnifying party is actually prejudiced by such failure to give
notice. In case any such action is brought against an indemnified party, unless
in such indemnified party's reasonable judgment a conflict of interest between
such indemnified and indemnifying parties may exist or the indemnified party may
have defenses not available to the indemnifying party in respect of such claim,
the indemnifying party shall be entitled to participate in and to assume the
defense thereof, with counsel reasonably satisfactory to such indemnified party
and, after notice from the indemnifying party to such indemnified party of its
election so to assume the defense thereof, the indemnifying party shall not be
liable to such indemnified party for any legal or other expenses subsequently
incurred by the latter in connection with the defense thereof, unless in such
indemnified party's reasonable judgment a conflict of interest between such
indemnified and indemnifying parties arises in respect of such claim after the
assumption of the defenses thereof, other than reasonable costs of
investigation. Neither an indemnified nor an indemnifying party shall be liable
for any settlement of any action or proceeding effected without its consent. No
indemnifying party shall, without the consent of the indemnified party, consent
to entry of any judgment or enter into any settlement which does not include as
an unconditional term thereof the giving by the claimant or plaintiff to such
indemnified party of a release from all liability in respect of such claim or
litigation. Notwithstanding anything to the contrary set forth herein, and
without limiting any of the rights set forth above, in any event any party shall
have the right to retain, at its own expense, counsel with respect to the
defense of a claim.

         (d)      The indemnification required by Section 11(a) and (b) hereof
shall be made by periodic payments of the amount thereof during the course of
the investigation or defense, as and when bills are received or expenses,
losses, damages or liabilities are incurred.

         (e)      If the indemnification provided for in this Section 11 is held
by a court of competent jurisdiction to be unavailable to an indemnified party
with respect to any loss, liability, claim, damage or expense referred to
herein, the indemnifying party, in lieu of indemnifying such indemnified party
hereunder, shall contribute to the amount paid or payable by such indemnified
party as a result of such loss, liability, claim, damage or expense as is
appropriate to reflect the proportionate relative fault of the indemnifying
party on the one hand and the indemnified party on the other (determined by
reference to, among other things, whether the untrue or alleged untrue statement
of a material fact or omission relates to information supplied by the
indemnifying party or the indemnified party and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
untrue statement or omission), or (ii) if the allocation provided by clause (i)
above is not permitted by applicable law or provides a lesser sum to the
indemnified party than the amount hereinafter calculated, not only the
proportionate relative fault of the indemnifying party and the indemnified
party, but also the relative benefits received by the indemnifying party on the
one hand and the indemnified party on the other, as well as any other relevant
equitable considerations. No indemnified party guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the Securities Act)
shall be entitled to contribution from any indemnifying party who was not guilty
of such fraudulent misrepresentation.

         (f)      Other Indemnification. Indemnification similar to that
specified in the preceding subsections of this Section 11 (with appropriate
modifications) shall be given by the Company and each Holder of Registrable
Securities with respect to any required registration or other qualification of
securities under any federal or state law or regulation or governmental
authority other than the Securities Act.

         12.      Miscellaneous

         (a)      Governing Law. This Agreement shall be governed by and
construed in accordance with the laws of the State of Delaware.

                                       13
<PAGE>   14

         (b)      Successors and Assigns. Except as otherwise provided herein,
the provisions hereof shall inure to the benefit of, and be binding upon, the
successors, assigns, executors and administrators of the parties hereto. In the
event the Company merges with, or is otherwise acquired by, a direct or indirect
subsidiary of a publicly-traded company, the Company shall condition the merger
or acquisition on the assumption by such parent company of the Company's
obligations under this Agreement.

         (c)      Entire Agreement. This Agreement constitutes the full and
entire understanding and agreement between the parties with regard to the
subjects hereof.

         (d)      Notices, etc. All notices or other communications which are
required or permitted under the Transaction Documents shall be in writing and
sufficient if delivered by hand, by facsimile transmission, by registered or
certified mail, postage pre-paid, or by courier or overnight carrier, to the
persons at the addresses set forth below (or at such other address as may be
provided hereunder), and shall be deemed to have been delivered as of the date
so delivered:

         If to the Company:         Healtheon/WebMD Corporation
                                    400 The Lenox Building
                                    3399 Peachtree Road
                                    Atlanta, Georgia 30326
                                    Attention:        Jack Dennison, Esq.

         With a copy to:            Nelson Mullins Riley & Scarborough, L.L.P.
                                    Bank of America Corporate Center
                                    Suite 2600
                                    100 North Tryon Street
                                    Charlotte, North Carolina 28202
                                    Attention:        H. Bryan Ives III, Esq.
                                                      C. Mark Kelly, Esq.

         All correspondence to the Purchaser shall be addressed as follows:

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

or at such other address as any party shall have furnished to the other parties
in writing.

         (e)      Delays or Omissions. No delay or omission to exercise any
right, power or remedy accruing to any Holder of any Registrable Securities,
upon any breach or default of the Company under this Agreement, shall impair any
such right, power or remedy of such Holder nor shall it be construed to be a
waiver of any such breach or default, or an acquiescence therein, or of or in
any similar breach or default thereunder occurring; nor shall any waiver of any
single breach or default be deemed a waiver of any other breach or default
theretofore or thereafter occurring. Any waiver, permit, consent or approval of
any kind or character on the part of any Holder of any breach or default under
this Agreement, or any waiver on the part of any Holder of any provisions or
conditions of this Agreement, must be in writing and shall be effective only to
the extent specifically set forth in such writing. All

                                       14
<PAGE>   15
remedies, either under this Agreement, or by law or otherwise afforded to any
holder, shall be cumulative and not alternative.

         (f)      Counterparts. This Agreement may be executed in any number of
counterparts, each of which shall be enforceable against the parties actually
executing such counterparts, and all of which together shall constitute one
instrument.

         (g)      Severability. In the case any provision of this Agreement
shall be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not in any way be affected or
impaired thereby.

         (h)      Amendments. The provisions of this Agreement may be amended at
any time and from time to time, and particular provisions of this Agreement may
be waived, with and only with an agreement or consent in writing signed by the
Company and by the holders of a majority of the number of shares of Registrable
Securities outstanding as of the date of such amendment or waiver. The Purchaser
acknowledges that by the operation of this Section 12(h), the holders of a
majority of the outstanding Registrable Securities may have the right and power
to diminish or eliminate all rights of the Purchaser under this Agreement.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

                                       15
<PAGE>   16

This Registration Rights Agreement is hereby executed as of the date first above
written.

                                    COMPANY:

                                    HEALTHEON/WEBMD CORPORATION

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

                                    PURCHASER:

                                    JANUS CAPITAL CORPORATION:

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

                                       16

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