WASHINGTON — U.S. banks earned less in the July-September quarter than they did a year earlier, marking their first year-over-year profit decline since the spring of 2009 when the country was still mired in the Great Recession.

The Federal Deposit Insurance Corp. said Tuesday the banking industry earned $36 billion in the third quarter, down $1.5 billion or 3.9 percent from the third quarter of 2012.

The FDIC said the earnings decline came primarily from a $4 billion increase in litigation expenses at a single institution.

The FDIC did not name the institution, but the JPMorgan Chase & Co. reached a $4.5 billion settlement with investors earlier this month which was the latest in a series of legal settlements for the nation’s largest bank over JPMorgan’s sales of mortgage-backed securities in the year preceding the 2008 financial crisis.

As the housing market collapsed between 2006 and 2008, millions of homeowners defaulted on high-risk mortgages. That led to billions of dollars in losses for investors who bought securities created from bundles of mortgages.

Half of the nation’s 6,891 insured banking institutions had year-over-year growth in earnings while half reported declines, the FDIC said in its quarterly report on the health of the industry.