The largest U.S. retail banks could lose $92 billion in deposits and $5.1 billion in revenues in the next year if consumers their defection to smaller banks and credit unions. Although customer frustration has declined in the last two years, 9.7 percent of account holders at large banks still might move their money to other institutions over the next 12 months, according to a study by Connecticut-based consulting firm cg42 of 3,600 customers at the top 10 retail banks. Most banks have failed to address customers' top complaint since the first survey in 2011: "egregious charges" that include penalty fees for using ATMs outside of a bank's network and fees for reordering checks. New regulations have cut into overdraft and debit card revenue, prompting retail banks to pile on other fees or raise the pricing on previously no-cost checking accounts. The study also found that big banks have generally failed to respond to customer complaints about overdraft charges and mistakes on bank statements. Still, bank vulnerability has slightly improved since 2011; the percentage of potential defectors fell from 33 percent to 26 percent. Fifty-six percent of customers are uncomfortable with how big banks have become; and 63 percent believe that banks only care about their own interests. The survey found that Citigroup was ranked worst in customer satisfaction.