While the U.S. Securities and Exchange reportedly investigates whether Yahoo Inc. should have disclosed two massive data breaches to investors earlier, corporate defense attorneys who are not involved with the matter say any charges would mark the first SEC case involving failure to disclose a data breach to shareholders.

The investigation, reported first by The Wall Street Journal, will examine whether Yahoo broke securities laws when it waited until 2016 to disclose two data breaches in which more than a billion users had their data compromised.