Trading in stock shares of interiors supplier Lear Corp. was halted today, without explanation.

As of 4:45 p.m., Lear had yet to make a statement to explain why trading in its stock was halted on the New York Stock Exchange at 10:40 a.m., with the last share price at $40.07.

Typically, a significant buyout offer would trigger such an event.

Lear's stock price and trading volume have skyrocketed since Monday, Feb. 5, when investor Carl Icahn made a $2.3 billion bid, at $36 a share, for seat and electronics maker.

Pzena Investment Management LLC CEO Richard Pzena, who believes Icahn's bid is half of what the company is worth, said today that a Pzena offer was not behind the halt in trading. He said he did not know why trading was halted.

Pzena has not made an offer for Lear.

Richard Pzena wrote a letter to Lear directors Monday, Feb. 5, complaining that Lear shares were worth nearly double the offer made for the company by Icahn.

In the letter, Pzena asked directors to reject the Icahn offer and remove Lear management from future discussions of the offer because of a potential conflict of interest. Icahn indicated in his offer that Lear management would stay on after a buyout.

The letter also said that Pzena controlled 6.8 million Lear shares, or about 10.1 percent of Lear's stock.

Lear, of Southfield, Mich., ranks No. 7 on the Automotive News list of top 100 global suppliers with worldwide original-equipment automotive parts sales of $17.09 billion in 2005.