The all-stock deal, announced by both companies Monday, values optionsXpress at $17.91 per share, a 17 percent premium over its $15.33 closing price on Friday. OptionsXpress shares jumped 15.6 percent on Monday, while Schwab shares rose 0.6 percent.

Under the terms of the deal, which is expected to close in the third quarter, each share of Chicago-based optionsXpress would be swapped for 1.02 shares of Schwab.

The deal is a nod to retail investors' increased comfort with using options contracts to speculate and hedge. U.S. options trading volume has grown strongly recent years.

Schwab's chief rival, TD Ameritrade Holding Corp., bought options specialist thinkorswim in 2009.

Options, like trading in foreign exchange, is an area that had not been embraced by mainstream investors in the past, said Alois Pirker, director of research at Aite Group, a research firm specializing in brokerages and securities markets.

"Mainstream investors are expanding their view of asset classes, and the Schwab deal is a reflection of that," he said.

Schwab has been under pressure the last two years as individual, or "retail," trading calmed down and as U.S. interest rates remained near-zero. pressuring revenues from client assets. But the company's shares are up 27 percent in the last six months, as investors see turnarounds on both of those fronts.

"Schwab is trading at a rich multiple," said Diego Perfumo, analyst at Equity Research Desk. "There's a lot of expectations built into the Schwab stock. Maybe they won't be able to deliver that growth organically, so they'd better go out and grow through acquisitions."

OptionsXpress had 385,200 client accounts and $8.1 billion in client assets at the end of last month.

San Francisco-based Schwab said the deal is expected to bring $80 million in "revenue and expense synergies" and boost earnings "modestly" over the first full year of combined operations."

"Options investors at Schwab tend to be among the larger, more active and longer-standing of our client relationships," Chief Executive Walt Bettinger said in a statement. "OptionsXpress brings a similar set of sophisticated, engaged clients..."

David Fisher, CEO of 10-year-old optionsXpress, will continue to lead the division as its president.

The deal comes as Schwab plans to increase its retail presence across the United States by opening branch offices staffed by independent brokers. The new offices, the first of which will open by the end of the year, will supplement Schwab's existing 300 retail branches.