Jeremy Siegel Says Get Ready to Buy

The "Wizard of Wharton" says don't worry.

"If investors have cash on the sidelines, they should not wait too long to put it to use," says Jeremy Siegel, Wharton business school professor at the University of Pennsylvania and well-known markets commentator. "There are good values out there in equities -- especially in financial stocks -- and you will be rewarded in the long run if you start dollar cost-averaging now."

To most investors, however, "the long run" seems a long way away when the market alternates daily between triple-digit gains and losses. Those wide swings are reflected in the spiking volatility index, or VIX, also commonly known as the "fear index," which has jumped from 12 to 26.5 over the past two months.

"Volatility is highest I can remember since 9/11," says Siegel. "Investors were spoiled by low volatility for so long, and they need to get used to it."

Once investors steel their stomachs to the market's waviness, Siegel says, exchange-traded funds, or ETFs, are the best way for them to put their toes in the water. ETFs are open-ended mutual funds, typically tracking an index, which can be traded like stocks throughout the course of the day.

Want more? Check out TheStreet.com TV video. Gregg Greenberg sat down with Wharton Professor Jeremy Siegel.

They are also a structure that Siegel knows quite well. When he is not in front of the blackboard at Wharton, he is the senior investment strategy adviser to the ETF provider Wisdom Tree Investments(WSDT.PK Quote).