THIS CERTIFIES THAT is the owner of CUSIP DATED COUNTERSIGNED AND REGISTERED: COMPUTERSHARE TRUST COMPANY, N.A. TRANSFER AGENT AND REGISTRAR, FULLY PAID AND NON-ASSESSABLE SHARES OF THE COMMON STOCK, $0.001 PAR VALUE PER SHARE, OF CELLDEX THERAPEUTICS, 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. COMMON STOCK PAR VALUE $0.001 COMMON STOCK THIS CERTIFICATE IS TRANSFERABLE IN CANTON, MA, JERSEY CITY, NJ AND COLLEGE STATION, TX SEE REVERSE FOR CERTAIN DEFINITIONS Certificate Number Shares . INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE President and Chief Executive Officer Senior Vice President and Chief Financial Officer By AUTHORIZED SIGNATURE 15117B 10 3 ZQ|CERT#|COY|CLS|RGSTRY|ACCT#|TRANSTYPE|RUN#|TRANS# DD-MMM-YYYY * * 000000* * * * * * * * * * * * * * * * * * * * * 000000* * * * * * * * * * * * * * * * * * * * * 000000* * * * * * * * * * * * * * * * * * * * * 000000* * * * * * * * * * * * * * * * * * * * * 000000* * * * * * * * * * * * * * ** MR. SAMPLE & MRS. SAMPLE & MR. SAMPLE & MRS. SAMPLE ZQ00000000 Certificate Numbers 1234567890/1234567890 1234567890/1234567890 1234567890/1234567890 1234567890/1234567890 1234567890/1234567890 1234567890/1234567890 Total Transaction Num/No. 123456 Denom. 123456 Total 1234567 MR A SAMPLE DESIGNATION (IF ANY) ADD 1 ADD 2 ADD 3 ADD 4 PO BOX 43004, Providence, RI 02940-3004 CUSIP XXXXXX XX X Holder ID XXXXXXXXXX Insurance Value 1,000,000.00 Number of Shares 123456 DTC 12345678 123456789012345

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 under Uniform Gifts to Minors Act . . . . . . . . . . . . . JT TEN - as joint tenants with right of survivorship UNIF TRF MIN ACT . . . . . . . . . . . . . . .Custodian (until age. . . ). . . . . . . . . . . and not as tenants in common (Cust) (Minor) under Uniform Transfers 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 Shares Attorney Dated: 20 Signature: Signature: 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 whatever. (Cust) (Minor) (State) PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE (PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING POSTAL ZIP CODE, OF ASSIGNEE) represented by the within Certificate, and do hereby irrevocably constitute and appoint to transfer the said shares on the books of the within-named Corporation with full power of substitution in the premises. . Signature(s) Guaranteed: Medallion Guarantee Stamp 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.