Las Vegas Horror Drives All-Too-Predictable Gun Stock Rally

The grim predictability of stock-market reactions to U.S. mass shootings—where before a final tally of casualties can be reached, shares of gun makers rise—continued Monday in the wake of a Las Vegas attack that killed at least 58 and wounded 515.

Historically, gun stocks have experienced a bump after a mass shooting for reasons both political and emotional. Gun sales typically rise over concerns that a deadly event could lead to more stringent gun-control legislation. An additional driver of sales, and by extension shares, is the rush by some consumers to purchase guns to defend against future attacks.

Authorities said that Stephen Craig Paddock opened fire from the 32nd floor of the Mandalay Bay Resort, high above a crowd attending the nearby Route 91 Harvest Festival concert. The shooter, originally reported to have been killed by officers, may have shot himself before they entered his hotel room, police said. As local hospitals worked to treat the injured, the south end of the iconic Las Vegas Strip was shut down. The motives of the 64-year-old white gunman remain unknown, police said.