Former Morgan Stanley brokerage adviser Kevin L. Dowd was charged with insider trading for tipping a friend ahead of Gilead Sciences Inc.’s $11 billion acquisition of Pharmasset Inc., U.S. prosecutors said.

Dowd, 37, who worked at a brokerage in Aventura learned that a Pharmasset director told Dowd’s superiors about the deal before it was announced on Nov. 21, 2011, according to a Federal Bureau of Investigation arrest complaint filed Monday.