The Los Angeles Angels are finalizing a 12-year, $430 million contract extension with Mike Trout, according to sources.

The deal would be the largest in professional sports history.

Trout, 27, would receive an average annual value of $36 million, topping Zack Greinke's previous record average of $34.4 million. The $430 million-plus total is more than 30 percent larger than the $330 million deal Bryce Harper signed with the Philadelphia Phillies on March 2.

Trout was due to be a free agent following the 2020 season.