Financial advisors will likely need to discuss the risks of options trading as the practice has been growing faster than overall stock trading, according to news reports.

While the total stock market trading volume has more than doubled since 2000, options trading volume has grown sixfold, the Wall Street Journal writes, citing data from Options Clearing Corp.

Option trades have also grown from 10% to 30% or more of total trade volume at online brokerages TD Ameritrade and E*Trade, according to the Journal, which cites estimates from investment bank Sandler O’Neill + Partners. Both firms have acquired options-trading platforms, the paper writes.

Much of the growing popularity comes from the brokerages themselves, as options trading is far more profitable than stock trading for the firms, according to the Journal.

Bid-ask spreads on options are wider for options than stocks, and trades happen frequently because options expire, the paper writes.

So, to attract more clients to options trading, TD Ameritrade has taken out TV ads touting that the firm “can walk you through your options trade step-by-step until you’re comfortable,” according to the Journal.

TD Ameritrade tells the paper that the ads are aimed at “sophisticated investors who are in the space currently or are interested in learning more via our education offerings” and that the majority of clients who trade options are “confident, informed investors” over the age of 45 with substantial assets.

But critics warn that investors can easily get wiped out, particularly when the options are used not for hedging existing positions but to reap profits from sudden price moves, according to the Journal. Selling unhedged calls or puts is particularly dangerous, the paper writes.

“It really is a form of gambling,” Robert Lowry, a former SEC commissioner, tells the Journal.

And Jeff Chiappetta, vice president of trading services at Charles Schwab, tells the paper that “over the long run, it’s hard to be profitable consistently on speculation alone.”

Around 20% of Schwab’s trading volume is in options, the Journal writes.