An investment banker charged with giving inside information about upcoming acquisitions by public companies says he shared secrets with his father but never thought he'd use it to trade stocks.

Sean Stewart testified Thursday at his Manhattan federal court trial. The 35-year-old Yale graduate says he spoke freely with his fiancee and his parents about his work as a vice president at JPMorgan Chase & Co. But he says he had no reason to believe his father would use information he shared to make money in the stock market.

Prosecutors say Stewart's father shared secrets he learned from his son with a broker who made over $1 million on trades. The father received about $150,000.

The father, Robert Stewart, pleaded guilty and is serving a year of home detention.