The trade deadline was instituted by MLB in response to various attempts by two New York City-based ballclubs, the Giants and Yankees, to use their financial advantages to tilt their respective leagues' competitive balance in their favor from 1917 through 1922. In the Yankees' case, most of its dealings were with the Boston Red Sox. The American League (AL) established MLB's first-ever such rule in 1920 as an indirect result of the Red Sox's sale of Babe Ruth to the Yankees.