The $17-a-share offer represents a 17 percent premium over the company’s Feb. 18 closing price. Icahn said the offer is contingent on Wilsonville, Oregon-based Mentor removing anti- takeover provisions, such as the company’s so-called poison pill.

Icahn called for the sale of the company, which helps engineers for electronic products work out design problems for chips, in an interview on CNBC earlier this month. Mentor has reported two straight annual net losses as its revenue fell from 2008 levels. Icahn is Mentor’s largest shareholder, according to Bloomberg data.

“We believe that there are potential strategic bidders for Mentor Graphics whose bid will reflect inherent synergies and should be superior to our $17 offer,” Icahn said in a letter to Mentor’s board.

Icahn runs an activist hedge-fund group, buys shares in companies he considers undervalued and then pushes management for changes to boost the stock prices. His targets have ranged from Time Warner Inc. and Motorola Inc. to small-cap stocks, including Lions Gate Entertainment Corp. Icahn’s fortune was valued at $11 billion by Forbes magazine last year.

Mentor jumped above the offer price, to as high as $17.38, in trading before exchanges opened in New York. The stock, which is up 21 percent this year before today, gained 6 cents to $14.52 in Nasdaq Stock Market trading on Feb. 18.