Baxter Leaving Jefferies.

Frank E. Baxter, who helped rebuild Los Angeles-based Jefferies Group Inc. into a stock-trading powerhouse after its founder pleaded guilty to fraud in 1987, said he would relinquish his chief executive title but remain active in the company as chairman.

Longtime Jefferies executive Richard B. Handler, 39, will become CEO and John C. Shaw, 53, will remain president and chief operating officer, titles the two men had shared since January.

The transition comes as Jefferies, like many brokerages, faces increasing competition from all-electronic trading systems that threaten the firm's core business of trading large blocks of stock for institutions. Currently, 80 percent of the 38-year-old firm's revenue comes from trading. Jefferies' traders specialize in negotiating transactions for big investors who want to buy or sell blocks of shares or bonds quickly and at the best possible prices.