SAN FRANCISCO ( TheStreet) -- Investors have good reason to be worried about the federal deficit but should also be wary of the stock market's rapid rise, a top Wells Fargo ( WFC) executive said on Wednesday. David Carroll, senior executive vice president and head of Wells Fargo's wealth, brokerage and retirement division sounded a word of caution about stocks, noting that the market has doubled in value at a faster clip than it has in over 50 years. The volatility in stock prices since the crisis erupted - with the market falling nearly as rapidly at times as it has risen - led Carroll to sound a word of caution to investors. "We're seeing a big and rather radical shift in flows out of fixed income - which we saw most of last year - and back into equities," Caroll said in an interview with TheStreet. "We think people need to be very thoughtful about that because the S&P 500 has doubled in less than 23 months, which is the fastest that it's doubled since the S&P 500 was compiled for the first time in 1957." Carroll, who was speaking to TheStreet about an investor-confidence index that's now sponsored by Wells Fargo, said investors have been shaken by episodes like the so-called "Flash Crash" last May and the European debt crisis, which occurred just as stocks were starting to stabilize. The Wells Fargo/Gallup Investor and Retirement Optimism Index, which launched on Wednesday, showed that the federal budget deficit is now tied at first place with unemployment among investor concerns. Of those polled by the partners, 71% said that the two issues were hurting the investment climate "a lot," followed by the price of energy, at 60%. Carroll said he wasn't surprised that the federal deficit was a concern, but was slightly stunned at how high it ranked among the worries of average investor. "Personally, I do think we all should be worried about the federal budget deficit," said Carroll. "I was surprised that it ranked where it did in the poll...I think you're seeing the good collective common sense of the U.S. taxpayer saying, 'Geez, if I can't afford too much debt, why can the government?'"