Wells Fargo disclosed on Friday that new account openings had taken a nose-dive since the scandal over illegal activity at the bank erupted: Bank executives said customers opened 25 percent fewer checking accounts and applied for 20 percent fewer credit cards in September compared with a year ago.

Wells Fargo executives acknowledged that customers may have shunned the bank as the extent of the problems came to light. Timothy J. Sloan, who was named the chief executive on Wednesday, said on the company’s third-quarter earnings call that he understood the gravity of the situation.

“As a new C.E.O., my immediate and highest priority is to restore trust in Wells Fargo,” Mr. Sloan said.

In other measures of the fallout, the bank said that a gauge of customer loyalty — which asks customers whether they would recommend Wells Fargo to family and friends — was also down in September.