Investment bank Stifel Financial Corp is reportedly in advanced talks to acquire Barclays' US wealth management unit in a deal that could come as early as next week.Stifel is currently negotiating key aspects with Barclays, although a deal is not certain and Barclays could go back to other bidders that have made offers, people familiar with the situation told Reuters.Barclays has been reaching out to potential buyers for the business for several weeks because it views it as non-core.Stifel has acquired several, mostly troubled retail brokerage and investment banking firms since 2005. A deal between Stifel and Barclays would come on the heels of Stifel's agreement in February to buy Alabama-based Sterne Agee Group for about $150m.Sterne Agee has about 730 brokers, who together with those now working at Barclays Wealth Americas, would bring the Stifel brokerage force to more than 3,000.