Barclays was slapped with its second fine in under a day after the Securities and Exchange Commission gave the British lender a penalty for compliance failings relating to the acquisition of part of the now-defunct Lehman Brothers.
Barclays will pay $15m (£9.2m, €11.7m) to settle SEC's charges and undertake remedial measures to improve its system, which includes hiring an independent compliance consultant.
"When a firm acquires an advisory business, it must devote the attention and resources necessary to build a robust compliance system," said Julie M. Riewe, co-chief of the SEC enforcement division's asset management unit.
"Barclays failed to establish this critical compliance foundation when it acquired Lehman's advisory business, and as a result subjected its clients to a host of improper practices and inadequate disclosures."
Only several hours earlier, the Financial Conduct Authority hit Barclays with a £37.7m fine for "failing to properly protect" £16.5bn worth of customers' assets.
The regulator added that, as a result of its "significant weaknesses" in the systems and controls in Barclays' Investment Banking Division between November 2007 and January 2012, clients risked incurring extra costs, lengthy delays or losing their assets if Barclays had become insolvent.