According to the efficient market hypothesis (EMH), a
company's stock price constantly adjusts to reflect all the currently available information about that
company. If the theory was correct, then there would be no such thing as an under- or over-valued stock. And
it would be impossible for a stock's return to beat the market's.
But in practice, some stocks seem to beat the overall market over long periods of time. Consider
Yahoo!. Over the last decade, Yahoo!'s stock price has climbed an impressive 2,500% while the S&P 500 has
mounted a less impressive 100% rise. Over the last year, however, Yahoo!'s stock has lost 4.3% of its value while
the S&P 500 increased 13%. Does Yahoo!'s short-term under-performance indicate that Yahoo!'s stock price is
likely to continue to tumble and that it ultimately will conform to the EMH's prediction?
I don't know the answer to this. One valuation theory that I've used is that a company's stock price is cheap
if its price/earnings ratio is lower than its earnings growth rate. And if the median of analysts' predictions for
its earnings in 2006 and 2007 are correct, Yahoo!'s earnings growth rate is higher than its price/earnings ratio.
Does this mean that Yahoo! stock is undervalued? Well, the consensus of 25 analysts polled by Zacks is that
that Yahoo!'s earnings will grow 36%, from 56 cents a share in 2006 to 75 cents/share in 2007. And Yahoo!'s P/E
on current earnings is 25.8. For those investors who prefer to compare the earnings growth to future earnings,
however, Yahoo! trades at a P/E of 58.9 -- making the stock overvalued at its current $32.30. But if you
believe in that valuation method, it would take a 58.9% earnings growth rate to justify Yahoo!'s current
stock price.