The Seattle Mariners and Chicago White Sox pulled off the biggest trade of 2026, two days before the Aug. 3 MLB trade deadline.The White Sox are acquiring starting pitcher Luis Castillo, a three-time All-Star, according to multiple reports. The Mariners will get reliever Seranthony Dominguez, outfielder Nolan Jones and catching prospect Boston Smith.Its a rare trade between two contending teams the White Sox are leading the American League Central, while Seattle is 2.5 games out of the third and final AL Wild Card berth.MORE: Mets make trade, begin trade deadline activity by sending reliever to TwinsMore to come on this story