SAN FRANCISCO ( TheStreet) -- Wells Fargo ( WFC) agreed to buy the entire North American factoring business of a GMAC subsidiary. Financial terms of the deal weren't disclosed. The portfolio, operated by the commercial services division of GMAC Commercial Finance Group, provides financing to small businesses. The portfolio consists of about 150 small- and middle-market clients that primarily serve retailers such as Wal-Mart ( WMT) and Target ( TGT), representing about $4 billion in annual volume of factored receivables, Wells Fargo said. Follow TheStreet.com on Twitter and become a fan on Facebook.