Exhibit 4.1

VI

INCORPORATED UNDER THE CUSIP 92529L 10 2

LAWS OF THE STATE

OF DELAWARE SEE REVERSE FOR CERTAIN DEFINITIONS

This certifies that

BY:

AMERICAN COUNTERSIGNED

is the record holder of STOCK

(NEW AND

FULLY PAID AND NONASSESSABLE SHARES OF COMMON STOCK, $0.0001 PAR VALUE, OFYORK,

VERSARTIS, INC. transferable on the books of the Corporation in person or by duly authorized attorney upon surrender of this Certificate properly TRANSFER

NY)&

endorsed. This Certificate is not valid until countersigned by the Transfer Agent and registered by the Registrar. REGISTERED: WITNESS the facsimile seal of the Corporation and the facsimile signatures of its duly authorized officers. TRUST

Dated: AUTHORIZED AND ARTIS, TRANSFERCOMPANY,

RS O IN

E RP RA C

V O T . LLC

C E

PRESIDENT & SIGNATURE REGISTRARAGENT

CHIEF EXECUTIVE OFFICER SEAL CORPORATE SECRETARY

DECEMBER 10, 2008

D E

E L AWAR

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 UNIF GIFT MIN ACT – ......................... Custodian ......................... TEN ENT – as tenants by the entireties (Cust) (Minor) JT TEN – as joint tenants with right of under Uniform Gifts to Minors survivorship and not as tenants Act (State) in common COM PROP – as community property UNIF TRF MIN ACT – ................. Custodian (until age ..................)

(Cust)

Additional abbreviations may also be used though not in the above list.

FOR VALUE RECEIVED, _____________________________________________________ hereby sell(s), assign(s) and transfer(s) 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 capital stock represented by within Certificate, and do hereby irrevocably constitute and appoint

attorney-in-fact to transfer the said stock on the books of the within named Corporation with full power of the substitution in the premises.

Dated

THE SIGNATURE(S) SHOULD 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. GUARANTEES BY A NOTARY PUBLIC ARE NOT ACCEPTABLE. SIGNATURE GUARANTEES MUST NOT BE DATED.

X

X

Signature(s) Guaranteed: NOTICE: THE SIGNATURE TO THIS ASSIGNMENT MUST CORRESPOND WITH THE NAME AS WRITTEN UPON THE

FACE OF THE CERTIFICATE IN EVERY PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT OR ANY

CHANGE WHATSOEVER.