Chip-equipment maker

Asyst

(ASYT)

announced late Wednesday that it has received a subpoena from the U.S. Department of Justice regarding its past stock-option practices, and that its stock could be delisted from the

Nasdaq

.

Asyst said it planned to appeal the delisting notice, which it expects to receive from the Nasdaq as a result of its delay filing its most recent annual report.

Earlier this month, the Freemont, Calif., company disclosed that the

Securities and Exchange Commission

was looking into its stock options granted from 1997 to the present, making Asyst the latest in a string of firms caught up in the widening controversy over the so-called backdating of stock options.

At the time, Asyst said the letter it received from the SEC stated that its actions did not mean any violation of law had occurred.

On Wednesday, Asyst said it had received a grand jury subpoena dated June 26 from the U.S. District Court in Northern California requesting documents about the company's stock-option grants from 1995 to the present.

Asyst said it is responding to the subpoena and intends to cooperate fully with the U.S. Attorney's office.

The company has launched an internal review of its past stock-option practices, which the company was not able to complete by Thursday. As a result, Asyst said it is in violation of Nasdaq regulations regarding the timely filling of financial reports.

Asyst said it anticipates that the Nasdaq will append the "E" character to its ticker symbol to denote the delinquency. The company said it is making every effort to complete its internal inquiry as soon as practicable.

Shares of Asyst were up 1%, or 7 cents, at $6.75 in midday trading Thursday.