UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): September 4, 2015

RAPTOR PHARMACEUTICAL CORP.

(Exact name of registrant as specified in its charter)

7 Hamilton Landing, Suite 100

Novato, California 94949

(Address of principal executive offices, including Zip Code)

Registrant’s telephone number, including area code: (415) 408-6200

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

On September 4, 2015, Raptor Pharmaceutical Corp. (the “Company”) entered into a Sales Agreement (the “Sales Agreement”) with Cowen and Company, LLC (“Cowen”) to sell shares of the Company’s common stock, par value $0.001 per share (the “Common Stock”), with aggregate gross sales proceeds of up to $75,000,000, from time to time, through an “at the market” equity offering program under which Cowen will act as sales agent.

Under the Sales Agreement, the Company will set the parameters for the sale of shares, including the number of shares to be issued, the time period during which sales are requested to be made, limitations on the number of shares that may be sold in any one trading day and any minimum price below which sales may not be made. Subject to the terms and conditions of the Sales Agreement, Cowen may sell the shares by methods deemed to be an “at the market” offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended (the “Securities Act”), including sales made through The Nasdaq Global Select Market, on any other existing trading market for the Common Stock or to or through a market maker. In addition, if expressly authorized by the Company, Cowen may also sell shares in privately negotiated transactions. The Sales Agreement may be terminated by the Company upon prior notice to Cowen or by Cowen upon prior notice to the Company, or at any time under certain circumstances, including but not limited to the occurrence of a material adverse change in the Company.

The shares will be issued pursuant to the Company’s shelf registration statement on Form S-3 (File No. 333-203095). The Company filed a prospectus supplement, dated September 4, 2015, with the Securities and Exchange Commission in connection with the offer and sale of the shares pursuant to the Sales Agreement.

The foregoing description of the material terms of the Sales Agreement is qualified in its entirety by reference to the full agreement, a copy of which is filed as Exhibit 1.1 to this Current Report on Form 8-K and is incorporated herein by reference.

The legal opinion of Latham & Watkins LLP relating to the shares of Common Stock that may be sold pursuant to the Sales Agreement is filed as Exhibit 5.1 to this Current Report on Form 8-K.

This Current Report on Form 8-K shall not constitute an offer to sell or the solicitation of any offer to buy the securities discussed herein, nor shall there be any offer, solicitation or sale of the securities in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Exhibit Index