Mutual fund pros, who gathered last week for one of the industry's biggest events, have a tough job: win back the investors who have soured on stocks.

Investors still are showing scars from the stock market meltdown of 2008. Normally, they put more than twice as much money into stocks than into bonds.

That's to be expected because they need the stock market's historically higher returns to build their retirement savings.

Yet over the past year and a half, investors have poured in a net $390 billion into taxable bond funds, while pulling out $45 billion from U.S. stock funds, according to Morningstar. All told, bond funds have taken in more than stock funds for 18 consecutive months.

It's a clear illustration of just how nervous investors are about market volatility, and how eager they are for the relative safety of bonds.

Consider that stocks have failed to draw new money even as the Standard & Poor's 500 index has climbed 65 percent since bottoming out in March 2009.

"Stocks kind of have to prove themselves all over again," says Kent Croft, co-manager of the top-performing Croft Value Fund (CLVFX). "March 2009 is still fresh in people's minds. It's human nature to avoid the source of the pain, and that source was stocks. So people are staying away from them."

After starting the year in a slump, the market rebounded only to hit another negative month in May, when stocks fell on fears about Europe's debt troubles and other bad news. Investors responded by pulling $15 billion out of stock funds, the largest monthly outflow since March 2009.

Some of the anxiety has subsided as stocks have since posted two consecutive weeks of gains. Still, there's a lot to fear as fund tracker Morningstar opened its 22nd annual conference Wednesday in its home city of Chicago. The event, which ran through Friday, drew 1,350 fund industry pros and financial advisers, up 20 percent from a year ago.

The fund industry has a lot at stake.

There's an undeniable self-interest to get investors back into stocks. Bond fund managers welcome their recent popularity because their fee revenue had grown. But generally, fund companies charge higher fees to invest in stocks rather than bonds because of the added complexity of stock-picking. So there's less fee money coming in overall.

One of the conference attendees, Chuck Akre, manager of the Akre Focus Fund (AKREX), ticks off a long list of worries that are turning investors away from stocks. Some of the same issues eventually could trigger higher interest rates and inflation that would crimp bond returns as well. There's the European debt crisis, persistently high U.S. unemployment, a weak housing market, growing government debt, the Gulf Coast oil spill and renewed tensions in hot spots such as Afghanistan, Israel and North Korea.

"While the economy is recovering, the world isn't getting better that quickly," says Akre.

Akre had a successful 13-year run managing the FBR Focus fund before leaving to start his own fund last year. He's playing it safe, holding about 30 percent of Akre Focus' $220 million in assets in cash. The remaining 70 percent is in nearly two dozen stocks.

The big cash stake, matching the highest percentage he's ever had in a 42-year investment industry career, could soften the blow if stocks tank again. If stocks come back, Akre will miss some of the gains, but he's not willing to take the risk.

"There are lots of reasons to be cautious, and we're keeping lots of dry powder," Akre says.