Dow 20,000 and the Problems Ahead for Stocks by Geoff Colvin @FortuneMagazine January 12, 2017, 10:35 AM EST E-mail Tweet Facebook Linkedin Share icons As the Dow keeps not quite hitting 20,000, the eternal debate over the market’s priciness is heating up. And while we’d all like to maintain a Warren Buffett-like serenity toward the market’s direction, most business leaders, as a practical matter, cannot. They have to decide whether it’s a good or a bad time for a company to buy back stock, to award employee stock options in large quantities or small, or to adjust their personal investments as retirement approaches. So let’s face the question: Are stocks today cheap or expensive? Articles arguing opposite sides have just been published, one in the Wall Street Journal (stocks are cheap), the other by Fortune’s own Shawn Tully (stocks are expensive). So as not to keep you in suspense, I’m going with Shawn, as I always do in matters of valuation, a policy that has served me extremely well over many years. The stocks-are-cheap argument proceeds from a few reassuring facts. Corporate profits are rising after having plunged over the past two years. The unexpected election of Donald Trump, which hadn’t been priced into the market until November 9, heralds an era of pro-business and pro-growth policy from Washington. More broadly, the financial crisis scared millions of investors away from stocks; now, as the business environment warms up, many of them will return, and the sheer volume of dollar inflow will push prices higher. It’s a plausible argument based on observable trends. But Shawn has never favored that type of argument. Instead, he dissects the numbers, and right now they are not comforting. The S&P 500 is trading at a PE multiple of 25.3, which is far above historical averages. That multiple could be perfectly rational, however, if profits are about to explode, and Wall Street analysts are indeed predicting a strong rise. So what’s the problem? Subscribe to Power Sheet, Fortune’s newsletter for leaders. The problem is that analysts tend to fall in love with the companies they analyze and overestimate future profits. If you aggregate their profit forecasts for the individual companies they cover, the result is usually way above the actual performance of the companies collectively – about seven percentage points above, says the FactSet research firm. The coming profit surge is by no means certain. The bulls like to note that certain industries should do much better this year, for example as rising oil prices benefit energy firms. But rising oil prices also impose higher costs and thus lower profits on other companies. Bottom line, I think Shawn makes the more persuasive argument. Stocks are not cheap. But I also try to remember that even when the market is irrational, it’s perfectly capable of getting more irrational. Alan Greenspan notes that an investor who bailed out of stocks when he gave his famous “irrational exuberance” speech in 1996 would have missed 80% of the bull market’s gains. I also try to remember that market milestones like Dow 20,000 are meaningless, and just because the index gets close to a round number doesn’t mean it’s about to hit that number. After all, investors got excited about Dow 1,000 when the index hit 969 in December 1965 – but it didn’t close above 1,000 for seven more years. Dow 20,000 could happen this afternoon, or years from now.