The Giants have made their first significant move ahead of the trade deadline, dealing reliever Ray Black and swingman Drew Pomeranz to the Brewers for a top middle-infield prospect, Mauricio Dubon, according to a major-league source.

Dubon, 25, is a right-handed hitter who has played some outfield. He was hitting .297 with 16 homers and an .809 OPS for Triple-A San Antonio.