Charles Schwab Corp (SCHW.N) on Thursday completed its $1 billion deal to acquire optionsXpress (OXPS.O), expanding its options and futures reach at a time when other brokerage sectors have stalled.

Separately, BMO Capital Markets reported on Thursday that U.S. options volumes reached a record in August, up 39 percent from July, and up 88 percent from a year earlier, at 24.2 million daily options contracts traded.

The San Francisco-based Schwab, one the largest financial services companies, agreed in March to buy optionExpress for $1 billion in stock.

Schwab, which has about 8.2 million client brokerage accounts and $1.65 trillion in client assets, adds OptionsXpress's 397,400 client accounts, $8.4 billion in client assets and a 12 month average of 44,900 daily average revenue trades, based on data for the first half of the year.

While it is much smaller than Schwab, optionXpress boosts the larger company's presence in an active trading sector that has grown strongly in recent years. Schwab's chief rival TD Ameritrade Holding Corp (AMTD.O) bought options specialist thinkorswim in 2009.

San Francisco-based Schwab said that work is underway to create a combined set of capabilities so that clients can log on to to see their optionsXpress account balances and easily move money between accounts.

Schwab clients looking to immediately access optionsXpress's trading features and platform can open an optionsXpress account, the firm said.

Overall trading volumes at U.S. retail brokerages jumped 30 percent in August from July due to a spike in market volatility, following the U.S. credit rating downgrade and amid ongoing concerns over global growth, BMO said.