Today’s WSJ summarizes the debate between Thaler, a leading skeptic of market efficiency, and Fama, the leading defending of the efficient capital markets hypothesis. As the article notes, the debate could have implications for privatizing social security. It quotes Thaler as saying, “[i]f you give people 456 mutual funds to choose from, they’re not going to make great choices.” The result may be that the securities markets get detached from fundamental values and misallocate resources.
Thaler concedes that “it is not easy to beat the market, and most people don’t.” This is an important point, since it follows that we have no alternative to accepting the wisdom of markets, even if it’s imperfect.
But even if we can’t beat the market, we should be concerned if the market is detached from real values, because then investment dollars would be misallocated. On this point Thaler has little doubt, saying that Fama “is the only guy on earth who doesn’t think there was a bubble in Nasdaq in 2000.” In fact, Fama’s not alone, as I’ve noted.
Assuming markets are inefficient in the weaker sense just noted, what should we do about it? Those who align with Thaler suggest that privatizing social security would further misalign securities prices from value by bringing more irrational investors into the market. The WSJ says that “in a rational world, share prices should move only when new information hit the market. But with more than one billion shares a day changing hands on the New York Stock Exchange, the market appears overrun with traders making bets all the time.”
My main point here is that this conclusion, if true, has implications beyond social security. As I’ve noted, our securities laws are based on the principle that markets should be safe for ordinary investors. If we’re really concerned about a lot of irrational investors running around, then we should be skeptical not only about privatizing social security, but about the securities laws as well. This would mean drastic revisions of disclosure rules, and being honest with investors and voters about what the securities laws are able to accomplish. Investors are either rational or irrational. Public policy should follow logically and consistently from whichever conclusion we choose to accept.
Originally posted by Larry Ribstein on Ideoblog.