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Exhibit 4.3

[FACE OF CERTIFICATE]
COMMON STOCK
NUMBER
FC
INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE
FASTCLICK, INC.
COMMON STOCK
SHARES
SEE REVERSE FOR CERTAIN DEFINITIONS
CUSIP 31188F 10 5
THIS CERTIFICATE IS TRANSFERABLE IN CANTON, MA, JERSEY CITY, NJ OR NEW YORK, NY
THIS CERTIFIES THAT
IS THE RECORD HOLDER OF
FULLY PAID AND NONASSESSABLE SHARES OF THE COMMON STOCK, $0.001 PAR VALUE PER SHARE, OF
FASTCLICK, 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 until countersigned and registered by the Transfer Agent and Registrar.

WITNESS the facsimile seal of the Corporation and the facsimile signatures of its duly authorized officers.

Dated:
/S/
CHIEF FINANCIAL OFFICER AND SECRETARY
[SEAL]
/S/
CHIEF EXECUTIVE OFFICER
COUNTERSIGNED AND REGISTERED:
EQUISERVE TRUST COMPANY, N.A.
TRANSFER AGENT AND REGISTRAR
BY:
AUTHORIZED SIGNATURE

[REVERSE OF CERTIFICATE]

The Corporation shall furnish without charge to each stockholder who so requests a statement of the powers, designations, preferences and relative participating, optional, or other special rights of each class of stock of the Corporation 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.

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
THE SIGNATURE(S) 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.

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Exhibit 4.3