Stifel is now negotiating key aspects with Barclays, although a deal is not certain and Barclays could go back to other bidders that have made offers, the people said this week.
A deal for the business - the former brokerage arm of Lehman Brothers - could come as early as next week, the people said.
The price being discussed could not be learned.
The sources requested anonymity because the matter is not public, and a spokeswoman for Stifel and a spokesman for Barclays declined to comment.
Barclays has been reaching out to potential acquirers for the business for several weeks because it views it as non-core, sources told Reuters.
Stifel Chairman and Chief Executive Ron Kruszewski has acquired several, mostly troubled retail brokerage and investment banking firms since 2005. The once low-key St. Louis firm that specialized in municipal bonds is now a national presence serving individual investors and middle-market companies.
Kruszewski, a fireman’s son who became CEO in 1997, has paid relatively low prices for the acquisitions, but often provides generous pay packages to retain employees of the firms.
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 $150 million.
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.