This weeks guest on the podcast Econtalk
is Eugene Fama, one of the giants of academic finance, specifically stock
market behavior. Fama is a professor at the University of Chicago
Below is a partial transcript of the
interview. I have highlighted the relevant lessons for investors – specifically
the strong evidence supporting the use of index funds.
Fama (Guest): Ken French and I just published a paper called "Luck Versus Skill in Mutual Fund Performance," and basically looked at performance of the whole mutual fund industry--in the aggregate, together, and fund by fund, and try to distinguish to what extent returns are due to luck versus skill. And the evidence basically says the tests it's skill in the extreme. But you've got skill in both extremes. That's something people have trouble accepting. But it comes down to a simple proposition, which is that active management in trying to pick stocks has to be a zero sum game, because the winners have to win at the expense of losers. And that's kind of a difficult concept. But it shows up when you look at the cross section of mutual fund returns, in other words the returns for all funds over very long periods of time. What you find is, if you give them back all their costs, there are people in the left tail that look too extreme and there are people in the right tail that look too extreme, and the right tail and left tail basically offset each other. If you look at the industry as a whole; the industry basically holds a market portfolio. That's all before costs. If you look at returns to investors then there is no evidence that anybody surely has information sufficient to cover their cost
Russ: Which says that for any individual investing, certainly someone like me, that is, who doesn't spend any time or very much time at all looking--in my case no time, but let's suppose even a little time--trying to look at what would be a good investment. The implication is to go with index mutual funds because actively managed funds can't outperform. Guest: Well, no, it's more subtle than that. What's more subtle about it is, even if you spent time, you are unlikely to be able to pick the funds that will be successful because so much of what happens is due to chance. Russ: So, for me the lesson is: buy index mutual funds because the transaction costs of those are the smallest, and since very few actively managed funds can generate returns with any expectation other than chance to overcome those higher costs, I can make more money with an index fund. Guest: Right. Now, it's very counterintuitive, because we look at the whole history of every fund's returns, and sort them, and really the ones in the right tail are really extreme. Russ: Some great ones.Guest: They beat their benchmarks by 3-6% a year. Nevertheless, only 3% of them do about as well as you would expect by chance. Now what's subtle there is that by chance, with 3000-plus funds, you expect lots of them to do extremely well over their whole lifetime. So, these are the people that books get written about. Russ: Because they look smart. Guest: What this basically says is that there is a pretty good chance they are just lucky. And they had sustained periods of luck--which you expect in a big sample of funds. Russ: Of course, they don't see it that way. Guest: No, of course not. Russ: A friend of mine who is a hedge fund manager--before I made this call I asked him what he would ask you, and he said, well, his assessment is that efficient markets explain some tiny proportion of volatility of stock prices but there's still plenty of opportunity for a person to make money before markets adjust. And of course in doing so, make that adjustment actually happen and bring markets to equilibrium. Somebody has to provide the information or act on the information that is at least public and maybe only semi-public. What's your reaction to that comment? Guest: That's the standard comment from an active manager. It's not true. Merton Miller always liked to emphasize that you could have full adjustment to information without trading. If all the information were available at very low cost, prices could adjust without any trading taking place. Just bid-ask prices. So, it's not true that somebody has to do it. But the issue is--this goes back to a famous paper by Grossman and Stiglitz--the issue really is what is the cost of the information? And I have a very simple model in mind. In my mind, information is available, available at very low cost, then the cost function gets very steep. Basically goes off to infinity very quickly. Russ: And therefore? Guest: And therefore prices are very efficient because the information that's available is costless.
