<PAGE>   1
                                                                   EXHIBIT 10.09


                           REVOLVING CREDIT AGREEMENT


   
         This Revolving Credit Agreement (this "AGREEMENT") is made and entered
into effective as of January 13, 1999 (the "EFFECTIVE DATE") by and between Data
Broadcasting Corporation, a Delaware corporation ("LENDER"), and
MarketWatch.com, Inc., a Delaware corporation ("BORROWER").
    


                                    RECITALS

         WHEREAS, Lender is a party to that certain Limited Liability Company
Agreement dated as of October 29, 1997, between CBS Inc., a New York corporation
("CBS") and Lender, with respect to Marketwatch.Com, LLC, a Delaware limited
liability company (the "LLC"), which provides, among other things, that Lender
shall provide to the LLC, on an unsecured, revolving basis, loans in amounts up
to $5,000,000 (the "REVOLVING LOAN");

         WHEREAS, pursuant to the terms of that certain Agreement and Plan of
Reorganization dated as of the date hereof, LLC will merge with and into the
Borrower (the "MERGER"), with Borrower to be the entity surviving the Merger;

         WHEREAS, Borrower and Lender desire that Lender's obligation to provide
the Revolving Loan shall survive the Merger;

         WHEREAS, Lender desires to loan certain sums to Borrower from time to
time, and Borrower wishes to borrow certain sums from Lender, on and subject to
the terms and conditions contained in this Agreement;

         NOW, THEREFORE, in consideration of the mutual promises,
representations, warranties, covenants and conditions set forth in this
Agreement and for other good and valuable consideration, the receipt and
adequacy of which are hereby acknowledged, Lender and Borrower hereby, intending
to be legally bound by the terms hereof, agree as follows:

         1.       CERTAIN DEFINITIONS.  As used herein:

                  1.1 BUSINESS DAY. The term "BUSINESS DAY" means any day other
than a Saturday, Sunday, or other day on which commercial banks in San
Francisco, California are authorized or required by law to close.

                  1.2 CREDIT PERIOD. The term "CREDIT PERIOD" means that period
of time beginning on the Effective Date and ending on October 29, 2000.

                  1.3 LOAN DOCUMENTS. The term "LOAN DOCUMENTS" means,
collectively, this Agreement, the Note (as defined below) executed and delivered
pursuant hereto, and any other documents executed or delivered by Borrower
pursuant to this Agreement or in connection with any Loan.


<PAGE>   2

                  1.4 MATURITY DATE. The term "MATURITY DATE" means that date
which is the earlier to occur of: (a) October 29, 2000; or (b) the date on which
Lender declares the entire unpaid principal amount and all accrued interest on
each outstanding Note immediately due and payable in full under Section 8.2(b).

         2.       AMOUNT AND TERMS OF CREDIT.

                  2.1 COMMITMENT TO LEND. Subject to all the terms and
conditions of this Agreement, and in reliance on the representations, warranties
and covenants of Borrower set forth in this Agreement, Lender agrees to make
loans of funds to Borrower during the Credit Period on a revolving basis (such
loans being collectively hereinafter referred to as "LOANS" and each
individually as a "LOAN"), in an aggregate cumulative total principal amount not
to exceed five million Dollars (US $5,000,000). Lender's obligation to make
Loans to Borrower under this Agreement is hereinafter referred to as the
"COMMITMENT." Notwithstanding the foregoing, Lender will not be obligated to
make a Loan to Borrower unless and until Borrower executes and delivers to
Lender a Note (as defined in Section 2.2) for the principal amount of such Loan.
In addition, Lender will not be obligated to advance any Loan to Borrower on or
after the Maturity Date, and Lender's obligation to advance any Loan to Borrower
is subject to satisfaction of all relevant terms and conditions of this
Agreement, including but not limited to the conditions precedent and other
provisions of Sections 5 (with respect to the initial Loan) and 6 (with respect
to each Loan). Notwithstanding the foregoing, Lender will not be obligated to
make a Loan to Borrower unless and until a Borrower first gives Lender written
notice of Borrower's request for a Loan hereunder that sets forth the principal
amount to the borrowed by Borrower under such requested Loan (a "LOAN NOTICE")
and the date on which such Loan is requested to be advanced, which date shall
not be sooner than five (5) Business Days following Lender's receipt of such
Loan Notice.

                  It is also agreed that amounts previously advanced by Lender
pursuant to Section 12.01 of the Limited Liability Company Agreement dated as of
October 29, 1997 shall be included as part of the Initial Loan.

                  2.2 NOTE. Borrower's indebtedness to Lender under each Loan
advanced by Lender under this Agreement will be evidenced by a separate
Promissory Note of Borrower in the form attached hereto as Exhibit "A" (the
"NOTE"). The Note will provide that interest on unpaid principal will accrue at
a rate equal to the prime rate as announced by The Chase Manhattan Bank as its
prime rate in effect at its principal office in New York City plus two percent
(2%) per annum (calculated on the basis of a 360-day year) compounded annually
(but in no event higher than the highest lawful rates).

                  2.3 MATURITY. Unless payment thereof is accelerated or
otherwise becomes due earlier under the terms of this Agreement (including but
not limited to the provisions of Section 8.2) or the terms of a Note the unpaid
principal amount of all Loans and all unpaid interest accrued thereon, together
with any other fees, expenses or costs incurred in connection therewith, will be
immediately due and payable to Lender in full on the Maturity Date.



                                       2
<PAGE>   3

                  2.4 PREPAYMENT. Borrower may at any time and from time to time
on any Business Day prepay any Loan in whole or in part in increments of U.S.
$1,000 on at least one (1) Business Day's prior written notice, or telephonic
notice promptly confirmed in writing, received by Lender no later than 10:00
a.m., Pacific Time. Each prepayment will be applied as follows: (a) first, to
the payment of interest accrued on all Loans outstanding, and (b) second, to the
extent that the amount of such prepayment exceeds the amount of all such accrued
interest, to the payment of principal on such Loan or Loans as Borrower may
designate.

         3.       CLOSING DATE; DELIVERY.

                  3.1 CLOSING DATE. The closing of the initial Loan (the
"CLOSING") will be held by mail and/or telecopy on the Effective Date (the
"CLOSING DATE"), or at such other time and place as Borrower and Lender may
mutually agree.

                  3.2 DELIVERY. At the Closing, Borrower will execute and
deliver to Lender the Note, duly executed by Borrower.

         4. REPRESENTATIONS AND WARRANTIES OF BORROWER. Borrower hereby
represents and warrants to Lender that:

                  4.1 ORGANIZATION AND STANDING; CHARTER DOCUMENTS. Borrower is
a corporation duly organized, validly existing and in good standing under the
laws of the State of Delaware, and has all requisite corporate power and
authority to own, lease and operate its properties and to conduct its business
as such is presently conducted and as proposed to be conducted. Borrower is duly
qualified to do business as a foreign corporation in good standing in any state
or jurisdiction in the United States in which it is required to be qualified to
do intrastate business as the Company's business is currently conducted, except
for jurisdictions in which failure to so qualify could not reasonably be
expected to have a material adverse effect on the business and operations of the
Company taken as a whole. True and accurate copies of the Certificate of
Incorporation (the "CHARTER") and Bylaws of Borrower, each as amended and
currently in effect, have been delivered to Lender and Lender's counsel.

                  4.2 AUTHORIZATION. All corporate action on the part of
Borrower and its officers, directors and stockholders that is necessary for the
authorization, execution, delivery and performance of each of the Loan Documents
by Borrower has been taken; and each of the Loan Documents, when executed and
delivered by Borrower, will constitute valid and legally binding obligations of
Borrower, enforceable in accordance with their terms.

         5. CONDITIONS PRECEDENT TO INITIAL LOAN. The obligation of Lender to
make the initial Loan under the Commitment is subject to the satisfaction (or
written waiver by Lender) of all the following conditions precedent:

                  5.1 REPRESENTATIONS TRUE. All representations and warranties
of Borrower contained in this Agreement and all other Loan Documents will be
true, correct and complete in all respects with the same effect as though such
representations and warranties had been made on 



                                       3
<PAGE>   4

and as of the Closing; and Lender will have received a certificate executed by
the President or Chief Executive Officer of Borrower certifying the foregoing.

                  5.2 NOTE. Lender will have received the Note representing the
initial Loan, executed by a duly authorized officer of Borrower.

                  5.3 CORPORATE DOCUMENTS. Lender will have received, in form
and substance satisfactory to Lender and its counsel, a copy of the records of
all actions taken by Borrower, including all corporate resolutions of Borrower
authorizing or relating to the execution, delivery and performance of the Loan
Documents and the consummation of the transactions contemplated thereby, and a
certified copy of the Charter of Borrower.

                  5.4 PROCEEDINGS AND DOCUMENTS. All corporate and other
proceedings in connection with the transactions contemplated by this Agreement
and all documents incident to such transactions will be in form and substance
satisfactory to Lender and Lender's counsel, and Lender will have received all
counterpart originals or certified or other copies of such documents as it may
reasonably request.

         6. CONDITIONS PRECEDENT TO ALL LOANS. The obligation of Lender to make
each Loan, including but not limited to the initial Loan, will be subject to the
satisfaction of all the following additional conditions precedent:

                  6.1 NO EVENT OF DEFAULT. No event will have occurred and be
continuing, and no event would result from the making of such Loan, that would
constitute an Event of Default as defined herein.

                  6.2 NOTE. Lender will have received the Note representing such
additional Loan, executed by a duly authorized officer of Borrower.

                  6.3 REPRESENTATIONS TRUE. All representations and warranties
of Borrower contained in this Agreement or in any other Loan Documents will be
true, correct and complete in all respects with the same effect as though such
representations and warranties had been made on and as of the date such Loan is
actually advanced (except to the extent such representations and warranties
specifically relate to an earlier date, in which case they will be true,
accurate and complete in all material respects as of such earlier date).

                  6.4 ALL AGREEMENTS PERFORMED. All agreements, obligations,
conditions and covenants set forth in this Agreement and all other Loan
Documents to be performed by Borrower through the date such Loan is advanced
will have been duly performed and complied with in all respects.



                                       4
<PAGE>   5



         7. OTHER COVENANTS OF BORROWER. Borrower hereby covenants and agrees
with Lender as follows:

                  7.1 FINANCIAL AND OTHER INFORMATION AND INSPECTION. Except as
provided in Section 7.3, until the Termination Date, Borrower will provide to
Lender all the reports and rights described below in this Section 7.1:

                           (a) Annual Financial Information. As soon as
practicable after the end of each fiscal year of Borrower, but no later than one
hundred twenty (120) days thereafter, an audited consolidated balance sheet of
Borrower and its subsidiaries as at the end of such fiscal year, and
consolidated statements of income and cash flows of Borrower and its
subsidiaries for such year, prepared in accordance with generally accepted
accounting principles and setting forth in each case in comparative form the
financial statements for the previous fiscal year, all in reasonable detail and
audited and certified by independent public accountants acceptable to Lender.

                           (b) Quarterly Financial Information. As soon as
practicable after the end of each fiscal quarter of Borrower, and in any event
within forty-five (45) days thereafter, an unaudited consolidated balance sheet
of Borrower and its subsidiaries as at the end of such quarter and consolidated
statements of income and cash flows of Borrower and its subsidiaries for each
such quarter and for the fiscal year to date, prepared in accordance with
generally accepted accounting principles, all in reasonable detail.

                           (c) Inspection Rights. The right to visit and inspect
any of the properties of Borrower or any of its subsidiaries, and to discuss its
and their affairs and finances with its and their officers, all at such
reasonable times and as often as may reasonably be requested by Lender.

                           (d) Other Information. With reasonable promptness,
such other information and data, including, without limitation, lists of
property and accounts, budgets, agreements with insurers, forecasts, tax returns
and reports, with respect to Borrower and its subsidiaries as may from time to
time may be reasonably requested by Lender, and all such other information and
communications (including, without limitation, notices of meetings of Borrower's
shareholders) as Borrower will have supplied to its holders of any shares of its
capital stock.

                  7.2 TERMINATION OF COVENANTS. The covenants set forth in
Sections 7.1 and 7.2 will terminate on the earlier of: (a) the date upon which a
registration statement filed by Borrower under the Securities Act of 1933, as
amended, in connection with a firm commitment underwritten public offering of
its securities first becomes effective and the securities registered thereunder
are sold; (b) the date Borrower first becomes subject to filing reports under
Section 13 or 15(d) of the Securities Exchange Act of 1934, as amended; or (c)
the repayment in full of all indebtedness under all Notes, provided that Lender
is under no further obligation to make any additional Loans hereunder.



                                       5
<PAGE>   6

                  7.3 FURTHER ASSURANCES. In addition to the obligations and
documents which this Agreement expressly requires Borrower to execute, deliver
and perform, Borrower will execute, deliver and perform, and will cause its
subsidiaries to execute, deliver and perform, any and all further acts or
documents which Lender may reasonably require in order to carry out the purposes
of this Agreement or any of the other Loan Documents.

         8.       EVENTS OF DEFAULT OF BORROWER.

                  8.1 EVENTS OF DEFAULT. The occurrence of any of the following
events will constitute an "EVENT OF DEFAULT":

                           (a) Borrower fails to pay any principal or any
accrued interest under any Note or any Loan when the same is due and payable, or
fails to pay any amount of principal or accrued interest due under any Note or
any Loan on the Maturity Date therefor, and such failure to pay is not cured by
Borrower within five (5) calendar days after Lender gives written notice of such
failure to pay to Borrower;

                           (b) any material representation or warranty made by
or on behalf of Borrower in this Agreement or in any other Loan Document, or any
statement or certificate that Borrower may at any time give in writing pursuant
thereto or in connection therewith is false, misleading or incomplete in any
material respect when made (or deemed to have been made);

                           (c) Borrower fails or neglects to perform, keep or
observe any covenant set forth in this Agreement or in any of the other Loan
Documents, and the same has not been cured within ten (10) calendar days after
Borrower becomes aware thereof;

                           (d) Borrower or any of its subsidiaries becomes
insolvent, or admits in writing its inability to pay its debts as they mature,
or makes an assignment for the benefit of creditors, or applies for or consents
to the appointment of a receiver, liquidator, custodian or trustee for it or for
a substantial part of its property or business, or such a receiver, liquidator,
custodian or trustee otherwise is appointed and is not discharged within thirty
(30) calendar days after such appointment; or

                           (e) bankruptcy, insolvency, reorganization or
liquidation proceedings or other proceedings for relief under any bankruptcy law
or any law for the relief of debtors are instituted by or against Borrower or
any of its subsidiaries, or any order, judgment or decree is entered against
Borrower or any such subsidiary decreeing its dissolution or liquidation;
provided, however, with respect to an involuntary petition in bankruptcy, such
petition is not have been dismissed within thirty (30) days after the filing of
such petition.

                  8.2 REMEDIES OF LENDER. Upon and after the occurrence of any
Event of Default, Lender will have no further obligation to make any Loan or
Loans to Borrower, and in addition, at Lender's sole option by written notice to
Borrower, Lender take any one or more of the following actions:



                                       6
<PAGE>   7

                           (a) Lender may immediately terminate the Commitment
and all liabilities and obligations of Lender under this Agreement, without
affecting Lender's rights under this Agreement and the Note(s);

                           (b) Lender may declare the entire principal amount of
and all accrued interest on the Note(s) and all Loans to immediately be due and
payable in full, whereupon such amounts will immediately become due and payable
in full, provided that in the case of an Event of Default listed in paragraph
(d) or (e) of Section 8.1, the principal and interest will immediately become
due and payable without the requirement of any notice or other action by Lender;
and

                           (c) Exercise all rights and remedies granted under
the Loan Documents or otherwise available to Lender at law or in equity.

         9.       MISCELLANEOUS.

                  9.1 SURVIVAL. The representations and warranties of Borrower
contained in or made pursuant to this Agreement and all the other Loan Documents
will survive the execution and delivery of the Loan Documents.

                  9.2 ENTIRE AGREEMENT. This Agreement, the Note, and the
exhibits and schedules attached hereto constitute the entire agreement and
understanding among the parties with respect to the subject matter thereof and
supersede any prior understandings or agreements of the parties with respect to
such subject matter.

                  9.3 SUCCESSORS AND ASSIGNS. The terms and conditions of this
Agreement will inure to the benefit of and be binding upon the respective
successors and assigns of the parties; provided, however, that neither party may
assign or delegate any of its rights or obligations hereunder or under any other
Loan Document or any interest herein or therein without the other party's prior
written consent.

                  9.4 NO THIRD PARTY BENEFICIARIES; CONSTRUCTION. Nothing in
this Agreement, express or implied, is intended to confer upon any third party
any rights, remedies, obligations, or liabilities under or by reason of this
Agreement, except as expressly provided in this Agreement. This Agreement and
its exhibits are the result of negotiations between the parties and has been
reviewed by each party hereto; accordingly, this Agreement will be deemed to be
the product of the parties hereto, and no ambiguity will be construed in favor
of or against any party.

                  9.5 GOVERNING LAW. This Agreement will be governed by and
construed in accordance with the internal laws of the State of California as
applied to agreements entered into solely between residents of, and to be
performed entirely in, such State, without reference to that body of law
relating to conflicts of law or choice of law.

                  9.6 COUNTERPARTS. This Agreement may be executed in two or
more counterparts, each of which will be deemed in original, but all of which
together will constitute one and the same instrument.



                                       7
<PAGE>   8

                  9.7 NOTICES. Any notice required or permitted under this
Agreement will be given in writing and will be deemed effectively given upon
personal delivery; upon confirmed transmission by telecopy or telex; or three
(3) days following deposit with the United States Post Office, by certified or
registered mail, postage prepaid, addressed:

                           To Borrower:

                           MarketWatch.Com, Inc.
                           825 Battery Street
                           San Francisco, CA  94111
                           Telephone:  (415) 733-0500
                           Telecopier:  (415) 392-1972
                           Attention:  J. Peter Bardwick

                           To Lender:

                           Data Broadcasting Corporation
                           3955 Point Eden Way
                           Hayward, CA 94545
                           Telephone: (510) 266-6000
                           Telecopier: (510) 266-6018
                           Attention:  Mark Imperiale

or at such other address as such party may specify by written notice given in
accordance with this Section.

                  9.8 MODIFICATION; WAIVER. This Agreement may be modified or
amended only by a writing signed by both parties hereto. No waiver or consent
with respect to this Agreement will be binding unless it is set forth in writing
and signed by the party against whom such waiver is asserted. No course of
dealing between Borrower and Lender will operate as a waiver or modification of
any party's rights under this Agreement or any other Loan Document. No delay or
failure on the part of either party in exercising any right or remedy under this
Agreement or any other Loan Document will operate as a waiver of such right or
any other right. A waiver given on one occasion will not be construed as a bar
to, or as a waiver of, any right or remedy on any future occasion.

                  9.9 RIGHTS AND REMEDIES CUMULATIVE. The rights and remedies of
Lender herein provided will be cumulative and not exclusive of any other rights
or remedies provided by law or otherwise.

                  9.10 SEVERABILITY. Any invalidity, illegality or
unenforceability of any provision of this Agreement in any jurisdiction will not
invalidate or render illegal or unenforceable the remaining provisions hereof in
such jurisdiction and will not invalidate or render illegal or unenforceable
such provision in any other jurisdiction.



                                       8
<PAGE>   9



                  9.11 ATTORNEYS' FEES. If any party hereto commences or
maintains any action at law or in equity (including counterclaims or
cross-complaints) against the other party hereto by reason of the breach or
claimed breach of any term or provision of this Agreement or any other Loan
Document, then the prevailing party in said action will be entitled to recover
its reasonable attorney's fees and court costs incurred therein.

IN WITNESS WHEREOF, the parties have duly executed and delivered this Agreement
as of the Effective Date.


MARKETWATCH.COM, INC.                      DATA BROADCASTING CORPORATION



By: /s/ J. PETER BARDWICK                  By: /s/ MARK F. IMPERIALE
   ----------------------------               --------------------------------
Title: Chief Financial Officer             Title: President
       and Secretary

ATTACHMENTS:
Exhibit A - Promissory Note





                 [SIGNATURE PAGE TO REVOLVING CREDIT AGREEMENT]


                                       9

<PAGE>   10

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), OR UNDER THE SECURITIES LAWS OF CERTAIN
STATES. THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND
RESALE AND MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE ACT
AND APPLICABLE STATE SECURITIES LAWS, PURSUANT TO REGISTRATION OR EXEMPTION
THEREFROM. INVESTORS SHOULD BE AWARE THAT THEY MAY BE REQUIRED TO BEAR THE
FINANCIAL RISKS OF THIS INVESTMENT FOR AN INDEFINITE PERIOD OF TIME. THE ISSUER
OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL IN FORM AND SUBSTANCE
SATISFACTORY TO THE ISSUER TO THE EFFECT THAT ANY PROPOSED TRANSFER OR RESALE IS
IN COMPLIANCE WITH THE ACT AND ANY APPLICABLE STATE SECURITIES LAWS.


                                    REVOLVING
                                 PROMISSORY NOTE


                            San Francisco, California


   
$5,000,000.00                                             January 13, 1999
    

   

         This Revolving Promissory Note (this "NOTE") is made and delivered
pursuant to that certain Revolving Credit Agreement dated as of January 13, 1999
between Borrower and Lender (as such terms are defined below), as such may be
amended from time to time (the "CREDIT AGREEMENT"). Unless otherwise defined
herein, all capitalized terms used in this Note shall have the same meanings
that are given to such terms in the Credit Agreement, the terms of which are
incorporated into this Note by reference.
    

   
         1. OBLIGATION. The undersigned, MarketWatch.com, Inc., a Delaware
corporation ("BORROWER") hereby promises to pay to the order of Data
Broadcasting Corporation, a Delaware corporation, ("LENDER" OR "HOLDER") on or
before October 27, 2000, at Lender's principal place of business at
3955 Point Eden Way, Hayward, CA 94545, or at such other place as Holder may
direct, the principal sum of five million Dollars ($5,000,000.00) or so much
thereof as may be advanced and outstanding, together with all interest accrued
on unpaid principal, to be computed on each advance of a Loan from the date of
its disbursement to Borrower, at a rate equal to the prime rate as announced by
The Chase Manhattan Bank as its prime rate in effect at its principal office in
New York City plus two percent (2%) per annum (calculated on the basis of a
360-day year), compounded annually. As used herein, the term "HOLDER" shall
initially mean Lender, and shall subsequently mean each person or entity to whom
this Note is duly assigned.
    

         The outstanding unpaid principal balance of this Note at any time shall
be the total principal amounts advanced hereunder by Holder less the amounts of
payments of principal made hereon by Borrower, which balance may be endorsed
hereon from time to time by Holder 


<PAGE>   11

in accordance with Section 2. Payments of interest on this Note shall be payable
on a quarterly basis, on the last business day of each calendar quarter.

         2. RECORDING OF LOANS AND PAYMENTS. Holder is authorized to record on
Schedule A hereto, and on any continuation(s) of such Schedule that may be
attached to this Note: (a) the date and principal amount of each Loan advanced
by Lender under the Credit Agreement; and (b) the date and amount of each
payment or prepayment of principal and/or accrued interest of any Loan; which
recordation will constitute prima facie evidence of the accuracy of the
information so endorsed on Schedule A; provided however, that any failure to
record such information on such Schedule or continuation thereof will not in any
manner affect the obligations of Borrower to make payments of principal and
interest in accordance with the terms of this Note. Holder will promptly provide
Borrower with a copy of each recordation made by Holder on Schedule A attached
hereto.

         3. PREPAYMENT. Prepayment of unpaid principal and/or interest due under
this Note may be made at any time without penalty as specified in the Credit
Agreement. Unless otherwise agreed in writing by Holder, all payments will be
made in lawful tender of the United States and will be applied (a) first, to the
payment of accrued interest, and (b) second, (to the extent that the amount of
such prepayment exceeds the amount of all such accrued interest), to the payment
of principal.

         4. DEFAULT; ACCELERATION OF OBLIGATION. Borrower will be deemed to be
in default under this Note and the outstanding unpaid principal balance of this
Note, together with all interest accrued thereon, will immediately become due
and payable in full, without the need for any further action on the part of
Holder, upon the occurrence of any Event of Default (as defined in the Credit
Agreement).

         5. REMEDIES ON DEFAULT; ACCELERATION. Upon any Event of Default, Holder
will have, in addition to its rights and remedies under this Note and the Credit
Agreement, full recourse against any real, personal, tangible or intangible
assets of Borrower, and may pursue any legal or equitable remedies that are
available to Holder, and may declare the entire unpaid principal amount of this
Note and all unpaid accrued interest under this Note to be immediately due and
payable in full.

         6. WAIVER AND AMENDMENT. Any provision of this Note may be amended or
modified only by a writing signed by both Borrower and Holder. Except as
provided below with respect to waivers by Borrower, no waiver or consent with
respect to this Note will be binding or effective unless it is set forth in
writing and signed by the party against whom such waiver is asserted. No course
of dealing between Borrower and Holder will operate as a waiver or modification
of any party's rights or obligations under this Note. No delay or failure on the
part of either party in exercising any right or remedy under this Note will
operate as a waiver of such right or any other right. A waiver given on one
occasion will not be construed as a bar to, or as a waiver of, any right or
remedy on any future occasion.



                                      -2-
<PAGE>   12

         7. WAIVERS OF BORROWER. Borrower hereby waives presentment, notice of
non-payment, notice of dishonor, protest, demand and diligence. This Note may be
amended only by a writing executed by Borrower and Holder.

         8. GOVERNING LAW. This Note will be governed by and construed in
accordance with the internal laws of the State of California as applied to
agreements between residents thereof to be performed entirely within such State,
without reference to that body of law relating to conflict of laws or choice of
law.

         9. SEVERABILITY; HEADINGS. The invalidity or unenforceability of any
term or provision of this Note will not affect the validity or enforceability of
any other term or provision hereof. The headings in this Note are for
convenience of reference only and will not alter or otherwise affect the meaning
of this Note.

         10. JURISDICTION; VENUE. Borrower, by its execution of this Note,
hereby irrevocably submits to the in personam jurisdiction of the state courts
of the State of California and of the United States District Court for the
Northern District of California that are located in San Francisco, California,
for the purpose of any suit, action or other proceeding arising out of or based
upon this Note.

         11. ATTORNEYS' FEES. If suit is brought for collection of this Note,
Borrower agrees to pay all reasonable expenses, including attorneys' fees,
incurred by Holder in connection therewith whether or not such suit is
prosecuted to judgment.

         12. ASSIGNMENT. This Note is not assignable by Holder without the
written consent of Borrower. This Note may not be assigned or delegated by
Borrower, whether by voluntary assignment or transfer, operation of law, merger
or otherwise.

         13. CREDIT AGREEMENT. This Note incorporates by reference all the
provisions of the Credit Agreement, including but not limited to all provisions
contained therein with respect to Events of Default, waivers, remedies and
covenants, and the description of the benefits, rights and obligations of each
of Borrower and Holder under the Credit Agreement.

         IN WITNESS WHEREOF, Borrower has executed this Note as of the date and
year first above written.

                                    BORROWER

                                    MarketWatch.com, Inc. a Delaware corporation

                                    By: /s/ J. PETER BARDWICK
                                        ----------------------------------------

                                    Name: J. PETER BARDWICK
                                         ---------------------------------------

                                    Title: Chief Financial Officer and Secretary
                                           -------------------------------------

<PAGE>   13
                                   SCHEDULE A
                                       TO
                            REVOLVING PROMISSORY NOTE
                                       OF
                              MARKETWATCH.COM, INC.

                     RECORD OF LOANS AND REPAYMENT OF LOANS


<TABLE>
<CAPTION>
                                    PRINCIPAL           AMOUNT             UNPAID
                  AMOUNT             AMOUNT               OF              PRINCIPAL
                    OF                 OF              INTEREST            BALANCE         NOTATION
   DATE          LOAN MADE         LOAN REPAID           PAID              OF LOAN         MADE BY
-----------    --------------    ----------------    -------------       ------------    -------------
<S>            <C>               <C>                 <C>                 <C>             <C>


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</TABLE>




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