Some $132 million in stock sales gains by the founder of the nation's biggest mortgage lender before the subprime crisis deepened has apparently caught the eye of regulators.

The Securities and Exchange Commission has opened an inquiry into sales by Countrywide Financial's chief executive, Angelo R. Mozilo, according to a number of reports today.

Mozilo sold his shares of Countrywide through a prearranged selling program for company insiders, known as a 10b5-1 trading plan. The pace of his sales, the New York Times says, picked up in October 2006, when a new 10b5-1 plan took effect.

Last week, the Times reported that the state treasurer of North Carolina, Richard Moore, had asked the S.E.C. to investigate, questioning changes that were made to Mozilo's stock sale program.

"As an investor and a Countrywide shareholder, I was shocked to learn that C.E.O. Angelo Mozilo apparently manipulated his trading plans to cash in, just as the subprime crisis was heating up and Countrywide's fortunes were cooling off,'' Mr. Moore wrote, according to the Times.

As the best-known face of the mortgage business, and with a rich, controversial pay package to boot, Mozilo is a natural target for those who want to point fingers amid the wreckage of the subprime market. (He took home an estimated $120 million in 2006.)

Yet there are significant questions about executive-selling plans in general, and the S.E.C. appears to be taking a broader look at their use. In a speech last week, the agency's director of enforcement,  Linda Chatman Thomsen, said,  "We are making sure that a rule designed to help executives with a legitimate purpose is not being used for illegitimate purposes."