On Wednesday, the occasion of its annual meeting, semiconductor maker Applied Micro Circuits announced that it had postponed the meeting until June 30.

The company stated that its audit committee, assisted by outside legal counsel, would review Applied Micro’s historical stock-option practices and related accounting. “This review is proactive and voluntary and was initiated in response to recently reported industry issues around option-pricing practices,” the company added, in a statement.

Rambus, which licenses computer memory technology, made a similar announcement late Tuesday. The company disclosed that its audit committee, as well as outside legal and accounting experts, will investigate the timing of past option grants and other potentially related issues. The probe is expected to focus primarily on options issued during or before 2003, according to the company.

Also on Tuesday, Sycamore Networks, which develops and markets optical networking products, disclosed that the U.S. Attorney’s Office for the District of Massachusetts has issued a grand jury subpoena for documents relating to stock-option grants. Sycamore added that it is cooperating with the investigation, as well as with a civil probe by the Securities and Exchange Commission, announced last week.