The SEC is reportedly expanding its probe into purchases of Sirius stock before the announcement that popular shock jock Howard Stern would join the company.

NEW YORK (CNN/Money) - The Securities and Exchange Commission is expanding a probe into whether anyone profited from news that popular shock jock Howard Stern will move to Sirius Satellite Radio, according to some published reports Wednesday.

The New York Post reported that the SEC is looking into whether Stern's driver, Ronnie Mund -- known on the show as "Ronnie The Limo Driver" -- bought stock of Sirius based on information that the deal was imminent.

The paper said that on Oct. 6, the day after the deal was announced, Stern told listeners that his driver had bragged in the studio about how he had bought Sirius (Research) stock cheap before the announcement.

The Post said Mund was not available for comment. It quoted a spokesman from Sirius as saying, "We have no reason to believe this matter involves Sirius or any actions of its officers, directors or employees, and neither Sirius nor any of its officers, directors or employees have received a subpoena in this matter."

Shares of Sirius jumped nearly 30 percent during the first day of trading after Stern's announcement of a five-year, $500 million deal with the satellite radio operator before closing up 16 percent on the day. The stock was also up about 11 percent in the week before Stern made the announcement, and 24 percent in the four weeks before the move was disclosed.

One of Stern's frequent guests, Chaunce Hayden, a gossip columnist for Steppin' Out magazine, told CNN last month he received a subpoena related to the SEC probe. He said that about a week or so prior to Stern's announcement, Hayden had predicted on another show that Stern would make the move to satellite radio, probably Sirius.

But he said his statement was not based on any inside information, and that he did not own any shares of Sirius.

The New York Daily News reported Wednesday that Hayden has been asked to turn over e-mails. The paper also reported that a Web site run by one of the shock jock's fans says that Stern lashed out at Hayden on the air, casting him as a publicity hound.