Also seems like a pretty big coincidence that the others sold off their shares immediately after hearing about the breach, but it was unrelated.
That has not yet been concluded. This could be the first move in a series of charges.
That or Ying was uniquely stupid. He texted his direct report “on the phone with [global CIO]. Sounds bad. We may be the one breached. . . . Starting to put 2 and 2 together" [1] before exercising "all of his vested options to buy Equifax shares, and then immediately [selling] those Equifax shares for total proceeds of more than $950,000" (§ 49) an hour after searching for "(1) 'Experian breach'; (2) 'Experian stock price 9/15/2015'; and (3) 'Experian breach 2015'" on the Internet (§ 42).
[1] https://www.sec.gov/litigation/complaints/2018/comp-pr2018-4... § 31