Exhibit 4.1 COMMON STOCK COMMON STOCK NUMBER SHARES HLT ADFORCE SEE REVERSE FOR CERTAIN DEFINITIONS INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE CUSIP 006867 105 THIS CERTIFIES THAT IS THE RECORD HOLDER OF FULLY PAID AND NONASSESSABLE SHARES OF THE COMMON STOCK, $0.001 PAR VALUE, OF ADFORCE, INC. transferable on the books of the Corporation by the holder hereof in person or by duly authorized attorney upon surrender of this certificate properly endorsed. This certificate is not valid unless countersigned by the Transfer Agent and registered by the Registrar. WITNESS, the facsimile seal of the Corporation and the facsimile signatures of its duly authorized officers. Dated: /s/ Rex S. Jackson [ADFORCE CORPORATE /s/ Charles W. Berger SECRETARY SEAL] CHAIRMAN AND CHIEF EXECUTIVE OFFICER COUNTERSIGNED AND REGISTERED: AMERICAN STOCK TRANSFER & TRUST COMPANY TRANSFER AGENT AND REGISTRAR BY AUTHORIZED SIGNATURE The Corporation will furnish without charge to each stockholder who so requests the powers, designations, preferences, and relative, participating, optimal, or other special rights of each class of stock or series thereof and the qualifications, limitations or restrictions of such preferences and/or rights. Such requests shall be made to the Corporation's Secretary at the principal office of the Corporation. KEEP THIS CERTIFICATE IN A SAFE PLACE. IF IT IS LOST, STOLEN, OR DESTROYED THE CORPORATION WILL REQUIRE A BOND OF INDEMNITY AS A CONDITION TO THE ISSUANCE OF A REPLACEMENT CERTIFICATE. The following abbreviations, when used in the inscription on the face of this certificate, shall be construed as though they were written out in full according to applicable laws or regulations: TEN COM -- as tenants in common TEN ENT -- as tenants by the entireties JT TEN -- as joint tenants with right of survivorship and not as tenants in common UNIF GIFT MIN ACT -- _______________ Custodian _______________ (Cust) (Minor) under Uniform Gifts to Minors Act _____________________________________ (State) UNIF TRF MIN ACT -- _______________ Custodian (until age_____) (Cust) ___________________under Uniform Transfers (Minor) to Minors Act ___________________________ (State) Additional abbreviations may also be used though not in the above list. FOR VALUE RECEIVED, ______________________ hereby sell, assign and transfer unto PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE - -------------------------------------- - -------------------------------------- ________________________________________________________________________________ (PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE) ________________________________________________________________________________ ________________________________________________________________________________ __________________________________________________________________________Shares of the common stock represented by the within Certificate, and do hereby irrevocably constitute and appoint ________________________________________________________________________Attorney to transfer the said stock on the books of the within named Corporation with full power of substitution in the premises. Dated ___________________ X_________________________________________________ X_________________________________________________ NOTICE: THE SIGNATURE TO THIS ASSIGNMENT MUST CORRESPOND WITH THE NAME(S) AS WRITTEN UPON THE FACE OF THE CERTIFICATE, IN EVERY PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATEVER. Signature(s) Guaranteed By _______________________________________________________ THE SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM) PURSUANT TO S.E.C. RULE 17Ad-15.