Babe Ruth to the Yankees (1920)

The Babe Ruth trade remains the most disastrous transaction in sports history: the Red Sox sold the greatest baseball player alive to the Yankees for $125,000, using the cash to fund a Broadway show. Ruth proceeded to smash 714 home runs and lead New York to seven pennants, while Boston endured an 86-year championship drought — a curse by every measure. This single deal outperforms #2 in sheer long-term fallout, as the Red Sox’s futility lasted decades beyond the Vikings’ regret. The trade yielded a 4,000% shift in franchise value, a concrete number that underscores its unmatched impact.