NFL adapts to crossover ownership
Although "not optimal", league accommodates
Owners with MLB, National Basketball Association or National Hockey League teams based in the same market as their NFL franchise would only be competing against themselves, yet the NFL would prefer that this not be the case, either, even if it has no rules against it.
http://www.buffalonews.com/sports/bills-nfl/nfl-adapts-to-crossover-ownership-20141008