On January 24, 2013, ARIAD Pharmaceuticals, Inc. (the "Company") entered into an underwriting agreement (the "Underwriting Agreement") with J.P. Morgan Securities LLC, Cowen and Company, LLC and Jefferies & Company, Inc., as representatives of the several underwriters (the "Underwriters") named in Schedule 1 of the Underwriting Agreement, related to a public offering of 15,307,000 shares of the Company's common stock, par value $0.001 per share (the "Common Stock"), at a public offering price of $19.60 per share less the underwriting discounts and commissions (the "Offering"). Under the terms of the Underwriting Agreement, the Company has granted the Underwriters an option, exercisable for 30 days, to purchase up to an additional 2,296,050 shares of Common Stock to cover over-allotments, if any, at the same price. The Offering is expected to close on or about January 29, 2013, subject to the satisfaction of customary closing conditions.

The net proceeds to the Company are expected to be approximately $287.5 million after deducting the underwriting discounts and commissions and estimated expenses associated with the Offering.

The Offering is being made pursuant to a prospectus supplement dated January 24, 2013 and an accompanying prospectus dated December 14, 2011, pursuant to the Company's automatically effective shelf registration statement on Form S-3 (File No. 333-178489), which was filed with the Securities and Exchange Commission on December 14, 2011.

A copy of the Underwriting Agreement is filed herewith as Exhibit 1.1 to this Current Report and is incorporated herein by reference. The Underwriting Agreement has been included to provide investors and security holders with information regarding its terms. It is not intended to provide any other factual information about the Company. The representations, warranties and covenants contained in the Underwriting Agreement were made only for purposes of such agreement and as of specific dates, were solely for the benefit of the parties to such agreement and may be subject to limitations agreed upon by the contracting parties, including being qualified by confidential disclosures exchanged between the parties in connection with the execution of the Underwriting Agreement. The representations and warranties may have been made for the purposes of allocating contractual risk between the parties to the agreement instead of establishing these matters as facts and may be subject to standards of materiality applicable to the contracting parties that differ from those applicable to investors. Investors are not third-party beneficiaries under the Underwriting Agreement and should not rely on the representations, warranties and covenants or any descriptions thereof as characterizations of the actual state of facts or condition of the Company or any of its subsidiaries or affiliates. Moreover, information concerning the subject matter of the representations and warranties may change after the date of the Underwriting Agreement, and this subsequent information may or may not be fully reflected in the Company's public disclosures.

A copy of the opinion of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. relating to the legality of the issuance and sale of the shares in the Offering is attached as Exhibit 5.1 hereto.

On January 24, 2013, the Company issued a press release announcing that it had priced the public offering described in Item 1.01 of this Current Report on Form 8-K. The Company's press release is filed as Exhibit 99.1 to this Current Report and is incorporated herein by reference.

The Company provided an updated description of its business in the prospectus supplement used in connection with the Offering. The updated business description is filed as Exhibit 99.2 to this Current Report and is incorporated herein by reference.

The Company also provided updated risk factors in the prospectus supplement used in connection with the Offering. The updated risk factors supersede in their entirety the risk factors included in the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2011 and the Company's subsequent Quarterly Reports on Form 10-Q. The updated risk factors are filed as Exhibit 99.3 to this Current Report and are incorporated herein by reference.

(d) Exhibits.

Exhibit
Number

 1.1         Underwriting Agreement dated January 24, 2013 by and among ARIAD
             Pharmaceuticals, Inc. and J.P. Morgan Securities LLC, Cowen and
             Company, LLC and Jefferies & Company, Inc., as representatives of the
             several underwriters named in Schedule 1 thereto.

 5.1         Opinion of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.

23.1         Consent of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
             (included in the opinion filed as Exhibit 5.1).

99.1         Press Release of ARIAD Pharmaceuticals, Inc., dated January 24, 2013.

99.2         Business Overview.

99.3         Risk Factors.