By Tim McLaughlin

NEW YORK (Reuters) - HSBC Holdings (HSBA.L: Quote, Profile, Research), Europe's biggest bank, said on Friday that it would close its U.S. subprime mortgage unit, cutting 750 jobs and taking $945 million (468 million pounds) in charges and write-downs, because the business is no longer sustainable.

For London-based HSBC, which is under pressure from activist investors to shake up its corporate governance, it was the latest blow from the meltdown in the U.S. market for loans to home buyers with poor credit histories.

HSBC Finance, the U.S. consumer finance arm of HSBC, said the closure of Decision One Mortgage would result in people losing their jobs at offices in Fort Mill, South Carolina, Phoenix, Arizona and Charlotte, North Carolina.

"It's no longer sustainable and not the right place to allocate capital in the future," HSBC Holdings Group Chief Executive Michael Geoghegan said in a statement.

Dozens of U.S. subprime lenders have curtailed operations, closed down or filed for bankruptcy protection. The subprime crisis has roiled the U.S. housing industry and played a central role in nearly 90,000 job cuts.

HSBC Finance will record an impairment charge of about $880 million, reflecting a write-down of Decision One assets on its books. It also will incur about $65 million in after-tax charges for restructuring that includes employee termination benefits and facility closures.

HSBC acquired Decision One when it bought Household International Inc. in 2003 for $14 billion. Decision One is a small part of HSBC's U.S. operations, which include auto lending and credit cards.

HSBC, the world's fourth biggest bank, with a market value of more than $200 billion, has been criticized for the underperformance of its share price in the last five years and its purchase of Household, which has exposed it to the U.S. subprime mortgage crisis.