For Bank of America, the spread is about 1.44 percentage points, data compiled by Bloomberg show.

Debt Holdings

U.S. commercial banks have increased their stakes in Treasuries and debt from federal agencies for 16 straight months, the longest stretch since 2003, data compiled by Bloomberg show. Together, they hold $2.1 trillion, the most according to Fed data going back to 1973.

The four biggest U.S. banks more than doubled their holdings of Treasuries to $251.8 billion last year, according to CompleteBankData.com, which analyzes data compiled from the Fed and Federal Deposit Insurance Corp.

Bank of America, the second-biggest U.S. lender, boosted investments almost 10-fold to $67.25 billion. Citigroup Inc.’s holdings rose by 60 percent to $110.38 billion, CompleteBankData.com figures show.

At the same time, lending hasn’t kept pace.

One of the biggest reasons is a lack of consumer demand for borrowing. While loans to businesses at U.S. commercial banks have risen 13 percent to $1.81 trillion, consumer loans increased just 5 percent to $1.2 trillion.

Deposit Growth

At Bank of America, consumer lending has contracted for four straight years, the longest slump since at least the mid-1990s, data compiled by Bloomberg show.

JPMorgan Chase & Co. has seen its consumer loans decrease in four of the past six years, while Wells Fargo & Co. reported an increase of less than 1 percent last year.