WILSONVILLE, OR -- Saying it remains open to proposals, Mentor Graphics declined an offer by its largest shareholder to buy the company outright.

In a statement today, Mentor said Carl Icahn's offer of roughly $1.9 billion undervalues the company. Icahn, who has been accumulating shares in the electronics design automation software developer for over a year, tendered the offer on Feb. 22, but left the door open to other bids.

In rebuffing Icahn, chairman and chief executive Wally Rhines noted Mentor's share price has grown more than 70% over the past year and about 200% in aggregate over the past two years.

“Our board believes that the continued execution of our strategic plan offers the greatest value to shareholders and that it will drive further growth and continued success,” said Rhines. He pointed out that Mentor achieved record sales in the fiscal year ended Jan. 31. "These outstanding results and our strong projections demonstrate that our strategy is working,” he said.

Mentor also noted that "serious regulatory risks persist" in any sale to Icahn.

Mentor said its board remains open to "any opportunity to enhance shareholder value," but did not elaborate on what those proposals might specifically entail.