Arizona will receive four of the Astros' top 30 prospects in exchange for Greinke. The boost to the Diamondbacks' farm system includes No. 3 prospect first baseman/outfielder Seth Beer, per MLB Pipeline, No. 4 right-handed pitcher J.B. Bukauskas, No. 5 righty Corbin Martin and No. 22 infielder Josh Rojas.
The New York Post's Joel Sherman reports that the Astros were not in Greinke's no-trade clause and he could not block the move.
News of Greinke's trade came just minutes after the trade deadline ended on Wednesday, the same day he took the mound for the Diamondbacks against the Yankees. In his final Diamondbacks start, Greinke gave up two runs and three walks with seven strikeouts in five innings at Yankee Stadium to slightly raise his ERA to 2.90.
Greinke is in the fourth season of a six-year, $206 million contract that runs through 2021. Rosenthal reports Houston will receive $24 million as part of the trade.
The Astros' move comes as they look to stay playoff contenders and hold their lead in the American League West. They entered Wednesday at 69–39 and are eight games ahead of the second-place Athletics.