(Forbes) Call it J.C Penney's private flash crash.
The stock today plunged 19.7% to close at $26.57. That's even worse than Black Monday 1987. On that day, the stock lost a hair less, 19.2%.
It's unclear if this is the stock's worst day ever. (Perhaps it suffered an even worse day during the 1930s.) However, it is clear that this is the worst single-day performance in the past 40 years. That's as far back as our FactSet data goes.
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