In 2 1/3 innings, Mariners hurler Gene Walter balks four times in a 12-3 loss to Detroit. The southpaw becomes the third American League pitcher to tie the major league record this season.

On July 18, 1988 — In 2 1/3 innings, Mariners hurler Gene Walter balks four times in a 12-3 loss to Detroit. The southpaw becomes the third American League pitcher to tie the major league record this season.

Source:
Baseball Reference July 18