The drug industry is showing signs it is slowing the pace of price increases after years of hefty hikes, alarming shareholders worried that pressure from politicians, consumers and employers will continue to stifle pricing power.

Shares of many drugmakers, wholesale distributors and pharmacy-benefit managers were battered Friday on new evidence in corporate earnings reports that pharmaceutical companies are declining to ratchet up prices as sharply as in previous years. McKesson Corp., one of the largest wholesale drug distributors,...