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): May 18, 2011

THE MOSAIC COMPANY

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (800) 918-8270

Not applicable

(Former Name or Former Address, if Changed Since Last Report)

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 (see General Instruction A.2. below):

The following information is being “furnished” in accordance with General Instruction B.2. of Form 8-K and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed to be incorporated by reference in any filing under the Securities Act of 1933, as amended (the “Securities Act”), or the Exchange Act, except as expressly set forth by specific reference in such filing:

The Mosaic Company issued a press release on May 19, 2011 announcing the pricing of a registered secondary offering of 100 million shares of common stock pursuant to a registration statement on Form S-1 filed by GNS II (U.S.) Corp. with the Securities and Exchange Commission. The offering, as well as the concurrent transactions relating to the recapitalization of Mosaic stock, is expected to close on May 25, 2011.

A copy of this press release is attached as Exhibit 99.1 and is incorporated by reference herein.

In addition, on May 18, 2011, GNS II (U.S.) Corp. filed an issuer free writing prospectus relating to the registered secondary offering containing information relating to trading and settlement of shares of Mosaic and GNS common stock through May 25, 2011.

A copy of the free writing prospectus is attached as Exhibit 99.2 and is incorporated by reference herein.

(d) Exhibits.

Reference is made to the Exhibit Index hereto with respect to the exhibits furnished herewith. The exhibits listed in the Exhibit Index hereto are being “furnished” in accordance with General Instruction B.2. of Form 8-K and shall not be deemed “filed” for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, nor shall it be deemed to be incorporated by reference in any filing under the Securities Act or the Exchange Act, except as expressly set forth by specific reference in such filing.

SIGNATURES

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

EXHIBIT INDEX