A sluggish month in the stock market has equity investors worrying about what's next.

But those equity investors would feel so much better if they'd just spend a little time studying the credit markets. And with good reason: The bull market in credit that continues to rage in the face of this stock-market lethargy leads us to one simple conclusion.

Stock prices have to head higher.

Indeed, independent analyst Brian Reynolds tells us that if stocks were trading at the same level as credit, the Standard & Poor's 500 Index would already be at 1,350 - 22% above where it closed on Friday.

For those who argue that the market has already rallied a great deal, or too much, let me just note that the S&P 500 would have to rise by another 41% just to get back to the level of three years ago. The key thing that bulls have in their back pocket is that investors are still trying to get used to the idea that the sky hasn't fallen - and have not yet priced in the prospects for a 25% increase in S&P 500 profits that we are likely to see in 2010.