“Locking the accounts is a good, safe measure,” Weissman said of Delta’s initial step. “But not communicating that fact to the affected customers can cause mass confusion and problems with people ...

Delta Air shares gained 6.3% to settle at $51.81 on Thursday. The Health Care Select Sector SPDR Fund gained 0.3% during Thursday's session. PayPal shares gained 3.5% to close at $80.08 on Thursday.