[2][3] After failing to acquire the St. Louis Cardinals baseball club in 1911, he became one of the founders of the upstart Federal League in 1913 as the owner of the Chicago Whales.

His restaurant empire began to fail as he spent much of his time and money on baseball and while the country moved away from "one-arm" lunch counters.

[2] At one point, Weeghman owned fifteen of these diners, with the one located at Madison and Dearborn serving 35,000 people each day.

Cardinals owner Helene Hathaway Britton had recently inherited the team upon the death of her uncle, Stanley Robison.

[10] He acquired an interest in the Chicago Cubs from Charles Phelps Taft in 1916, emerging as the older club's majority owner for $500,000 (approximately $14,000,000 today).

The Cubs board authorized up to $200,000 to acquire star players from other teams and Weeghman spent lavishly on them, paying $50,000 to buy the contracts of Grover Cleveland Alexander and Bill Killefer from the Philadelphia Phillies in 1917.

He reportedly considered making an offer to Brooklyn for Zach Wheat and tampered with Heinie Groh of Cincinnati.

[12] Over time, his lunch counter chain lost favor with the public and Weeghman was forced to sell more and more of his stock in the Cubs to chewing gum magnate William Wrigley Jr. to raise money.

[14] In October of that year, during the investigation of the Black Sox scandal Weeghman told reporters that he had been tipped off in August 1919 that the 1919 World Series would be fixed.

[20] Osmund and Weeghman remained married until he suffered a fatal stroke on November 1, 1938, at the Drake Hotel in Chicago.