KEY POINTS
  • Shares of Equifax tumbled in after-market trading Thursday and during market hours on Friday, falling nearly 14 percent, to $122.
  • Equifax options trade infrequently, with just under 260 contracts in July, roughly 13 a day.
  • On August 21, 2,600 contracts were bought giving the owner the right to sell Equifax shares at $135 in September.

Unusual trading in options in mid-August suggests millions of dollars in profit were generated after Thursday's disclosure of a massive data breach at the credit reporting company affecting 143 million consumers and their personal information.

Shares of Equifax tumbled nearly 14 percent on Friday in the wake of the disclosure of the breach. Until Thursday, they had been up about 20 percent for the year.