Periodic antitrust attacks on corporations may have influenced stock prices. For the period 1904 to 1944, each antitrust case filed is associated with a 0.5 to 1.9 percent drop of the Dow, and each unexpected case with even larger drops. Other aspects of antitrust besides actual filings may help account for other movements, in particular the 1929 Crash. Historical evidence bears on the question of whether antitrust is exogenous and also links antitrust and the “corporation problem.” These results illustrate the sorts of real factors aside from changes in concurrent output that may account for stock price volatility.

Periodic antitrust attacks on corporations may have influenced stock prices. For the period 1904 to 1944, each antitrust case filed is associated with a 0.5 to 1.9 percent drop of the Dow and each unexpected case with even larger drops. Other aspects of antitrust besides actual filings may help account for other movements, in particular the 1929 Crash. Historical evidence bears on the question of whether antitrust is exogenous and also links antitrust and the "corporation problem." These results illustrate the sorts of real factors, aside from changes in concurrent output, that may account for stock price volatility.

Periodic antitrust attacks on corporations may have influenced stock prices. For the period 1904 to 1944, each antitrust case filed is associated with a 0.5 to 1.9 percent drop of the Dow, and each unexpected case with even larger drops. Other aspects of antitrust besides actual filings may help account for other movements, in particular the 1929 Crash. Historical evidence bears on the question of whether antitrust is exogenous and also links antitrust and the “corporation problem.” These results illustrate the sorts of real factors aside from changes in concurrent output that may account for stock price volatility.