In exchange, the Blues will receive two draft picks in the 2020 NHL Draft - Washington's third-round pick and Chicago's seventh-round pick, both of which were previously acquired by the Canadiens. The Blues will also send their seventh-round pick in 2022 to Montreal.
"I want to personally thank Jake for his dedication to the St. Louis Blues organization during his entire time as a Blue," said Armstrong. "He has always been a top-tier professional who has done everything we have asked of him. We wish Jake and his wife Shannon nothing but the best in Montreal."
Allen was drafted by the Blues in the second round (34th overall) in the 2008 NHL Draft. He has played his entire career with St. Louis, posting a 148-94-26 record, a 2.50 goals-against average and a .913 save-percentage in 289 career regular-season games.
Allen ranks second all-time in franchise history in shutouts (21), trailing only Brian Elliott (25).