“While the wall-shaped schedule of future maturities is nothing new for the high-yield issuer universe, it is more front-loaded today,” the analysts said. “This could result in additional default pressures further down the road as issuers deal with a higher concentration of maturities than they what they have been dealing with in the past.”

The looming payments stem from companies shifting their loans to shorter maturities of three to five years, compared with five to seven years in the past, they said.

Banks stung by $1.7 trillion of writedowns and losses are more reluctant to lend to the neediest borrowers with ratings below Baa3 by Moody’s Investors Service and BBB- by Standard & Poor’s, according to data compiled by Bloomberg. Leveraged loans to U.S. companies shrank 81 percent in 2009 from their peak of $913.5 billion in 2007, the data show.

Debt maturities are “a point of particular concern in our view, given that primary loan issuance remains challenged by declining bank lending,” the analysts said.