Item 7.01 Regulation FD Disclosure.

On January 23, 2013, Cubist Pharmaceuticals, Inc., or the company, issued a press release reporting its results for the year and quarter ended December 31, 2012 and held a conference call to discuss those results. On the January 23 conference call, the company presented guidance for 2013 financial performance. The company incorrectly presented 2013 "Other Income (expense)" guidance as approximately $27 million of expected income rather than approximately $27 million of expected expense.

This report on Form 8-K contains a forward-looking statement regarding 2013 other income (expense). This guidance is subject to risks and uncertainties that could cause actual results to differ materially from those discussed. Such risks and uncertainties include the risk that our future financial and operating results will differ materially from our currently projected results, and those additional factors discussed under the heading "Risk Factors" in our quarterly report on Form 10-Q filed with the Securities and Exchange Commission for the third quarter of 2012. We caution investors not to place considerable reliance on our financial guidance. We undertake no obligation to update or revise any such statements.

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