UBS Fiduciary Trust, which is based in New Jersey, caters to about 800 retirement and employee benefit plans and has $5 billion in assets under administration. The deal will boost Wilmington Trust's Retirement and Institutional Services group to more than 3,800 plans serviced and $46 billion in assets.

The transaction, which is subject to regulatory approval, will have "little effect" on Wilmington Trust's staffing levels, the bank said in a regulatory filing.

Earlier this year, Wilmington completed a purchase of AST Capital Trust Company, a business located in Arizona.