Fraud allegations are proving contagious for regional banks, even when the infected party keeps saying they’re fine. Western Alliance BancorpWAL

and Zions BancorpZION

disclosed borrower fraud on Thursday, detonating a sector-wide banking panic. The news intensified concerns over loan quality and pushed Treasury yields lower amid broader market risk.

• Utah-based Zions flagged “apparent misrepresentations and default” on $60M in loans and has filed suit in California, while Western Alliance reported fraud tied to $100M in missing collateral.
• Wells Fargo analyst Timur Braziler captured the shoot-first mentality, noting, “When credit risk is rising, you just sell off the entire group and you get answers to your questions later.”

Cockroach theory gains traction: JPMorgan CEO Jamie Dimon’s warning that “when you see one cockroach, there are probably more” is haunting investors following recent bankruptcies. Fresh memories of the 2023 Silicon Valley Bank collapse — when rising rates torpedoed bond portfolios and sparked deposit runs — have traders questioning whether loose lending standards during boom times are coming home to roost. Both Western Alliance and Zions report earnings this week, with credit quality likely to dominate investor scrutiny as the sector enters a deluge of quarterly results.