Sienna Biopharmaceuticals, Inc. – Indentures Watch

from 8-K 11 pages Warrant to Purchase Common Stock

from 8-K 11 pages Warrant to Purchase Common Stock

from S-3 51 pages Sienna Biopharmaceuticals, Inc. Indenture Dated as of , 20 Wilmington Trust, National Association Trustee

from S-1/A 2 pages Number Siennatm Biopharmaceuticals Shares See Reverse Side for Certain Definitions Incorporated Under the Laws of the State of Delaware Cusip 82622h 10 8 This Certifies That Is the Owner of Fully Paid and Non-Assessable Common Shares, $0.0001 Par Value, of Sienna Biopharmaceuticals, Inc. Transferable on the Books of the Corporation by the Holder Hereof in Person or by Attorney Upon Surrender of This Certificate Properly Endorsed. This Certificate Is Not Valid Until Countersigned and Registered by the Transfer Agent and Registrar. in Witness Whereof, the Said Corporation Has Caused This Certificate to Be Signed by Facsimile Signatures of Its Duly Authorized Officers. Dated: Timothy K. Andrews General Counsel & Secretary Frederick C. Beddingfield III President & Chief Executive Officer Countersigned and Registered: Wells Fargo Bank, N.A. by Todd J. May Transfer Agent and Registrar Authorized Signature