Based in Seattle, ShareBuilder is a privately held brokerage and will be added to ING's on-line banking arm ING Direct in a deal that is expected to close by year-end.
ING stated the deal was equivalent to 27 basis points of the group's debt equity ratio. The company saidING Direct would absorb 661,000 ShareBuilder customers.
"ING's direct banking expertise, combined with ShareBuilder's on-line 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.