https://www.cnbc.com/2018/07/26/facebook-shares-may-rebound-after-plunge-just-likephilip-morris-in-ea.html

A quarter-century ago, one of the most important stocks in the market lost a quarter of its value in a single day after the company drastically reduced expectations for its long-term profitability. Its main product was viewed as addictive and nearly immune to competition, and investors complacently believed stellar long-term growth was almost inevitable.

The company was Philip Morris, and April 2, 1993, became known as "Marlboro Friday" after it suddenly cut the price of its flagship cigarette brand by 20 percent, buckling to intense competition from generic smokes.