— ] Shares Mast Therapeutics, Inc. Common Stock PURCHASE AGREEMENTPurchase Agreement • June 5th, 2013 • Mast Therapeutics, Inc. • Pharmaceutical preparations • New York
Mast Therapeutics, Inc., a Delaware corporation (the “Company”), proposes to sell to the several Underwriters named in Schedule I hereto (the “Underwriters”) an aggregate of [ — ] shares (the “Firm Shares”) of Common Stock, $0.001 par value per share (the “Common Stock”), of the Company. The Firm Shares consist of [ — ] authorized but unissued shares of Common Stock to be issued and sold by the Company. The Company has also granted to the Underwriters an option to purchase up to [ — ] additional shares of Common Stock on the terms and for the purposes set forth in Section 3 hereof (the “Option Shares”). The Firm Shares and any Option Shares purchased pursuant to this Purchase Agreement are herein collectively called the “Securities.”
