WASHINGTON — Sen. Edward M. Kennedy yesterday asked the Securities and Exchange Commission to investigate whether officials of big student lender SLM Corp. engaged in illegal insider trading in selling company stock ahead of the release of President Bush's budget proposal.

Kennedy, who heads the Senate panel that oversees educational issues, asked for an official review of the stock sales, and whether any members of the Bush administration "were complicit in such violation," in a letter to SEC Chairman Christopher Cox.

Kennedy noted that the budget proposal made public Feb. 5 included billions of dollars of cuts in government subsidies to the student lending industry that could crimp the profits of SLM, better known as Sallie Mae, the biggest player in the industry.

The SLM chairman, Albert L. Lord, sold $18.3 million of company stock Feb. 1 and Feb. 2. After the Bush proposal for the 2008 budget year was announced on Feb. 5, the stock plummeted 9 percent, to $42.37 a share.

SLM disclosed Lord's sale of 400,000 shares in a filing that night with the SEC, as required by law for officers and directors of public companies. He sold the stock to pay for personal projects, according to the filing, and an SLM spokesman said at the time that Lord had planned the sale for several weeks and had informed the company of his plans.

"Such trading activity immediately prior to the budget announcement ... raises obvious concerns about whether SLM officers and directors had inappropriate communications with members of the administration about the content of the president's budget before its public announcement," wrote Kennedy, D-Mass., who is chairman of the Senate Health, Education, Labor and Pensions Committee.

SEC spokesman John Nester declined comment.

Tom Joyce, a spokesman for Reston, Va.-based SLM, said Tuesday that Lord's stock sale "was utterly and completely coincidental in terms of the timing of the president's budget" and that the proposed reductions in subsidies were a surprise to the company.

"The stock sale had literally nothing to do with the president's budget," Joyce said.