Senate Majority Leader Bill Frist (search) said Tuesday he is "cooperating fully" with federal investigators probing his sale of stock in a large health care company founded by his father, but declined to say whether he has been subpoenaed or personally answered questions in the case.

"I acted properly at every point. I am absolutely confident of the outcome itself," said the Tennessee Republican, whose decision to order the sale of stock from his blind trusts in June is under review by both the Securities and Exchange Commission and federal prosecutors.

Frist directed the sale of his stock in HCA, Inc., about two weeks before the for-profit health care firm issued a disappointing earnings forecast that drove its share price down almost 16 percent. At the same time, top executives and directors of the company were selling shares totaling $112 million in value.

Frist has denied acting on insider information. He has previously said he wanted to divest himself of shares in the company to avoid the appearance of a conflict of interest at a time when he was preparing for a possible 2008 presidential campaign.

The lawmaker rarely discusses the investigations in public, but made himself available to reporters before the Senate convened for the day and appeared ready to field questions on the issue.

"I am cooperating fully with the inquiries under way. I acted properly at every point. I am absolutely confident of the outcome itself," he said.

At the same time, he said it would not be proper to say whether he has been subpoenaed or made himself available to answer questions personally.

HCA was formed by Frist's father and brother.