Anna confirmed the news on his personal twitter account:
Anna, 27, broke into the majors for the first time this season, notching three hits (including a homer) in 22 at-bats with the Yankees. He played shortstop, second base and even pitched during twelve major league games with the team, and hit .192 in 36 games at Triple-A Scranton/Wilkes Barre.
Anna will provide infield depth for the Pirates at Triple-A, and will be valued primarily for his defensive versatility. In parts of seven minor league seasons in the Padres and Yankees' organizations, he is a lifetime .280 hitter with 41 HR and 262 RBI while making only 82 errors.