TD Ameritrade CEO: Investors Rebalance, Seek Buying Opportunities

Instead of heading for the exits, investors are using Tuesday's massive sell-off as an opportunity to rebalance their portfolios and add to their stock positions, Joe Moglia, chief executive officer of TD Ameritrade, told CNBC's Maria Bartiromo.

Active traders were adding to their positions, Moglia said, notably in international equities. And, "for people who just had a (broad) allocation abroad, it gave them an opportunity to see where they needed to rebalance and, in some cases, it was to lighten up on their international exposure. After a 12-month run, it makes sense to lighten up to keep your allocations in whack."

The worst thing an investor can do, he said, is get emotional. "It's a matter of staying disciplined in difficult market enviornments," Moglia said. "And, for the most part, I think the average retail investor is doing that today."