ARIAD Pharmaceuticals, Inc. (NASDAQ:ARIA) announced today that its Board of Directors has adopted a shareholder rights plan in the form of a Section 382 Rights Agreement designed to preserve its substantial tax assets. As of December 31, 2012, ARIAD had tax assets, including net operating loss carryforwards of $307.7 million and research tax credits of $17.8 million, which could be used in certain circumstances to offset ARIAD’s future taxable income or otherwise payable taxes and therefore reduce its federal and state income tax liabilities. ARIAD’s plan is similar to plans adopted by numerous other public companies with significant tax assets. ARIAD’s ability to use these tax assets and others which may be generated would be substantially limited in the event of an “ownership change” under Sections 382 and 383 of the Internal Revenue Code and related U.S. Treasury regulations. In general, an ownership change would occur if ARIAD’s shareholders who own, or are deemed to own, 5% or more of ARIAD’s common stock increase their collective ownership in ARIAD by more than 50% over a rolling three-year period. The shareholder rights plan is intended to reduce the likelihood of an unintended ownership change occurring through the buying of ARIAD common stock. As part of the plan, on October 31, 2013, ARIAD’s Board declared a dividend of one preferred-share-purchase-right for each share of ARIAD common stock outstanding as of November 11, 2013. Effective today, if any person or group acquires 4.99% or more of the outstanding shares of ARIAD common stock, or if a person or group that already owns 4.99% or more of ARIAD common stock acquires additional shares representing 0.5% or more of the outstanding shares of ARIAD common stock, then, subject to certain exceptions, there would be a triggering event under the plan. The rights would then separate from the ARIAD common stock and would be adjusted to become exercisable to purchase shares of ARIAD common stock having a market value equal to twice the exercise price, resulting in significant dilution in the ownership interest of the acquiring person or group.