Barclays has agreed a settlement of 97 million dollars (£75 million) over allegations it overcharged more than 2,000 of its investment bank clients.
The US Securities and Exchange Commission (SEC) said it took enforcement action against Barclays Capital over alleged violations that the organisation said saw clients overcharged by nearly 50 million dollars (£39 million).
The SEC said it found two of the British lender's advisory programmes charged fees to more than 2,000 clients for services that were not performed as sold.
These included advisory clients who invested in third-party investment managers and investment strategies which under-performed while they were not monitored, the SEC said.
The bank also allegedly collected excess charges on the sales of investment funds from 63 brokerage clients by recommending more expensive share classes when less expensive options were available, while another 22,138 accounts overpaid due to alleged miscalculations and billing errors by the firm.
Without admitting or denying the findings, Barclays agreed to set up a fund, including a 30 million dollar (£23 million) penalty, to repay the clients.
Catherine O'Riordan, co-chief of the SEC Enforcement Division's Asset Management Unit, said: "Barclays failed to ensure that clients were receiving the services they were paying for.
"Each set of clients who were harmed are being refunded through the settlement."
A spokesman for Barclays declined to comment.
The settlement comes as the lender completes a swingeing overhaul of its business, including offloading parts of its investment and wealth management arms in Hong Kong and Singapore.
In February, the company announced pre-tax profits had surged to £3.2 billion, up from £1.1 billion a year earlier, thanks to a boost from its investment banking arm, as well as lower fines and mis-selling charges.
Chief executive Jes Staley, who has been offloading unwanted businesses to focus on UK and US operations, said at the time the group had "accomplished a lot in a year".