Wells Fargo & Co., aiming to translate home-lending clout into bigger profits, is building a team to package and trade mortgage-backed securities and curb reliance on Wall Street firms as a market recovery takes hold. The lender named Mike Buttner to head the residential loan- backed securities unit and expanded its mortgage-bond desk to 30 employees from five, Tim Mullins, 45, head of fixed-income trading at the San Francisco-based company, said in an interview yesterday. The bank expects the market for securitizations to strengthen by year’s end after investor demand for loans lacking government guarantees collapsed during the credit crisis.