Dutch financial services group ING has agreed to buy ShareBuilder Corporation's online brokerage business for $220 million to extend its reach in the United States, ING said on Tuesday.

ShareBuilder, a privately held brokerage based in Seattle, will be added to ING's online banking arm ING Direct in a deal that is expected to close by the end of 2007, the bank said.

ING, which reports third-quarter results on Wednesday, said the deal was equivalent to 27 basis points of the group's debt equity ratio.

It said ING Direct would absorb 661,000 ShareBuilder customers.

ING's direct banking expertise, combined with ShareBuilder's online brokerage expertise will facilitate a smooth integration and maximization of synergies to achieve ING Direct's growth targets, it said in a statement.

ING Direct is a key driver of the bank's earnings. Its U.S. arm, set up in 2000, has 6 million customers. ING Direct also operates in Canada, Australia, France, Spain, Italy, Britain, Austria and Germany where it has another 15 million customers.

ING shares were up 0.1 percent at 29.65 euros at 3:17 a.m. EST, compared to a 0.6 percent stronger DJ Stoxx European insurers index.

(Reporting by Niclas Mika and Emma Thomasson, editing by Paul Bolding)