Carl Icahn has sued AmTrust Financial Services Inc. over the company's pending go-private transaction that the investor is "strongly against."

According to a lawsuit filed in Delaware's Court of Chancery, the transaction undervalues the company and is taking place "at the wrong price and at the wrong time." Icahn asserted that the deal is an attempt to take control of a company poised to make a recovery and post earnings growth.

Icahn also accused the company and its controlling families of manipulating the record date, which may give them an advantage in a shareholder vote.

Icahn owns about 18.4 million AmTrust shares, or a 9.4% stake. AmTrust did not immediately respond to a request for comment.