Three lawyers, including a supporter of Wesley Clark (search), are requesting an inquiry by federal regulators into Howard Dean's (search) sale of about $15,000 in stock in five Vermont banks in 1991, arguing that the then-governor may have engaged in insider trading.

The three complaints to the Securities and Exchange Commission (search) in Washington and the U.S. attorney's office in Burlington, Vt., follow news reports about Dean's decision to sell the shares more than a decade ago when some Vermont banks were experiencing financial problems.

Dean said he sold the stock because "it became clear to me that information I might receive in the future as governor could present a possible conflict of interest."

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The statute of limitations is five years on criminal cases and civil fines for insider trading violations, putting Dean's sale well past the time for any such action by prosecutors and regulators. But the SEC could still take limited action if it chose to do so.

For example, if the SEC is able to prove charges of trading on inside information against someone for long-ago conduct, it can then ask a court to issue an order not to engage in the conduct in the future, at the risk of criminal contempt of the court.

One of the three attorneys filing the complaints, Michael Spadea, donated $50 to Clark's campaign and is a county coordinator is Connecticut for Clark's bid for the Democratic presidential nomination.

"This is the worst kind of 11th-hour dirty tricks by Wesley Clark's campaign," said Dean spokesman Jay Carson.

Clark's press secretary, Bill Buck, responded: "It's time for Dean to come clean and stop seeing shadows on the wall."

Spadea says he filed the complaint after reading news accounts of Dean's bank stocks.

SEC spokesman John Heine declined to comment.

The other attorneys filing the complaints are Christopher J. Frisco, a local prosecutor in Los Angeles County, Calif.; and Michael Ng, who works for a law firm in New York City. Frisco, Ng and Spadea all say they filed the complaints of their own volition.