State Street Corp. said Tuesday it would buy a unit of Goldman Sachs Group Inc. for $550 million that will help it become the leading provider of services to the hedge fund industry.

The new business, Goldman Sachs Administration Services, administers about $200 million in hedge fund assets for about 150 investment management clients. State Street already services $877 billion for alternative asset managers — a group that includes hedge fund managers, private equity firms, and real estate funds, with hedge funds making up the largest share of that business.

The combined operations would make State Street the top administrator to hedge funds, jumping ahead of current leader Citco Fund Services.

“Servicing alternative assets remains a strategic focus for State Street,” said George Sullivan, an executive vice president. More than 3,000 State Street employees in offices around the world work in a unit serving alternative asset managers.

Administrators such as State Street handle routine back-shop chores and paperwork for investment managers. They help calculate the value of fund assets and produce daily profit and loss statements, among other tasks.

Many hedge funds once handledtheir own administrative duties, but the Bernard Madoff Ponzi scheme scandal changed the industry, and regulators and investors have been pushing hedge fund managers to hire third-party administrators.

And as that business has grown, State Street and Citco have emerged as the dominant players.

The two will have roughly half of the $2 trillion-plus hedge fund administration market. Another player in the field is also growing by acquisition; SS&C Technologies Holdings earlier this month bought another large administrator, GlobeOp Financial Services, for about $809 million.

Together they administer hedge funds managing about $227 billion.

The Goldman acquisition follows the 2009 purchase by State Street of Mourant International Finance Administration, which added another $170 billion in assets from hedge funds and private equity firms.