September 3, 2013 (Shareholders Foundation) - An investor who currently holds shares of Onyx Pharmaceuticals, Inc. (NASDAQ:ONXX) filed a lawsuit in effort to halt the proposed takeover of Onyx Pharmaceuticals, Inc. by Amgen for $125 per NASDAQ:ONXX share.

The plaintiff alleges that the defendants breached their fiduciary duties by ageing to sell Onyx Pharmaceuticals too cheaply to Amgen.

On Jun. 30, 2013, Onyx Pharmaceuticals, Inc. (Nasdaq: ONXX) confirmed that it has received and rejected an unsolicited proposal from Amgen Inc. to acquire all of Onyx Pharmaceuticals’ outstanding shares and share equivalents for $120 per share in cash, subject to due diligence and other conditions. Then on Aug. 25, 2013, Amgen (NASDAQ:AMGN) and Onyx Pharmaceuticals, Inc. (NASDAQ:ONXX) announced that their Boards of Directors have unanimously approved a transaction under which Amgen will acquire all of the outstanding shares of Onyx Pharmaceuticals, Inc. for $125 per share in cash.

However, the plaintiff claims that the offer is too low and undervalues the company. Indeed, after the June 30, 2013 announcement NASDAQ:ONXX shares jumped in the open market to $136.03 per share on July 5, 2013. Moreover, the plaintiff alleges that the offer price is significantly below the $160-target prices for Onyx Pharmaceuticals’ stock set by analysts.

Furthermore, the plaintiff says that the process is unfair as well. The plaintiff claims that the defendants agreed to preclusive deal protection devices, such as a $303 million termination fee.

On September 3, 2013, NASDAQ:ONXX shares closed at $123.74 per share.