Star mutual fund manager John Hussman, president of Hussman Investment Trust, has been bearish on stocks for some time, and he's not changing his tune now. He's also not too enthusiastic about bonds.

"We continue to observe dispersion in market internals, a widening of credit spreads, and other features of market action that . . . convey a subtle but measurable shift toward risk-aversion among investors, in an environment where risk premiums remain razor thin," he writes in his weekly market commentary.

"Speculative yield-seeking has driven asset prices higher in recent years to the point where many asset classes now provide no risk premium at all." The best equity valuation measures stand at more than twice their pre-bubble norms, Hussman says.

So what's the outlook from here?

He predicts a 1.7 percent annual return during the next 10 years for a portfolio with "anything close to a standard mix of equities, bonds and cash."

Hussman's research indicates that "never in history, prior to the past five weeks, have the prospective 10-year nominal annual total returns of stocks and Treasury bonds been below 2 percent at the same time."

When it comes to stocks, Tom Lee, co-founder of FundStrat Global Advisors, disagrees with Hussman.

"I'm bullish, and I think it's an up year in a horizon where we'll have several more years of gains," he told CNBC. Lee projects the S&P 500 will end the year at 2,325, up 13 percent from Tuesday's level of 2,055.

"This is a bull market that's been around for a long time [six years], and I think it's frustrating people, because it's been hard to beat and it's been volatile," Lee said. "I think that type of frustration makes it easier for the market to surprise to the upside."

Companies are due to increase their capital expenditures, which should provide a boost for stocks, he said.

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