Maxim Integrated Products ( MXIM) joined the growing list of companies saying that regulators want more information about past awards of stock options. The company said Monday that it received a subpoena from the U.S. Attorney for the Northern District of California asking for documents relating to its option grants and practices. Maxim plans to cooperate with the request. Additionally, Maxim said it was cooperating with a similar, previously disclosed request from the Securities and Exchange Commission. The integrated circuits maker has authorized a review of its option grants, which is being conducted by a special committee of the board with the assistance of outside independent legal advisers. Dozens of companies, many of them members of the tech sector, are voluntarily examining their option programs or getting requests from regulators about their past awards. In several cases, questions have arisen about whether some companies backdated options for employees in order to have them correspond to low share prices. Maxim released the information after the markets closed at 1 p.m. EDT in observance of the Independence Day holiday in the U.S. Shares of Maxim rose 14 cents, or 0.4%, to $32.25 in regular trading.