The number of Long Island homeowners whose mortgage debt surpassed their homes' value surged last year.
Nearly 1 in 10 Long Islanders with mortgages -- 9.9 percent, or 53,639 households -- owed more than their homes were worth at the end of 2012. That share was up 3.1 percentage points from the same time in 2011, when 36,594 households were "upside down" on their mortgages, according to a report Tuesday by CoreLogic, a national data provider.
Long Island homeowners' increasing financial distress comes even as the rest of the country lowers its so-called negative equity, a term for when mortgage balances outweigh home values. Nationwide, 10.4 million homes with mortgages were in negative equity at the end of 2012, down from 12.1 million a year earlier.
However, the country as a whole still fares worse than Long Island, as 21.5 percent of national homeowners were underwater on their mortgages at the end of last year, down from 25.2 percent at the end of 2011.
It's not clear yet how much superstorm Sandy, which struck on Oct. 29, contributed to the increase in negative equity on the Island. The storm damaged nearly 58,000 homes here and saddled many owners with huge rebuilding costs.
The number of Long Island homes with upside-down mortgages, however, was rising even before the storm hit. In late September, 9.3 percent of Nassau and Suffolk homeowners with mortgages owed more than their homes were worth, up 2.5 percentage points from the same period in 2011, CoreLogic said.
The company tracks data on more than 85 percent of mortgages in the United States.
The storm's impact is likely to show up more in the coming months, after the expiration of the 90-day mortgage payment grace period that many homeowners got in the wake of the storm, said Lisa Cammarata, underwriting manager at Continental Home Loans in Melville.
Long Island's troubled real estate market hits poor and minority communities especially hard, said Marianne Garvin, chief executive of Community Development Corp. of Long Island. "The housing market is still suffering," she said, "and in many communities it has not only not rebounded, but it may still be falling."