Barron’s interviewed James Montier of Jeremy Grantham’s GMO over the weekend. Montier is a member of the GMO asset allocation team. Below are the highlights.

Barron’s: Bonds are expensive, stocks are expensive. What’s an asset allocator to do?

Montier: Things just don’t add up. One group has thrown in the towel and says, “If you can’t beat them, join them. I’m just going passive and be damned.” [Passive investing] is a very strange thing to do at this particular point in time.

The U.S. market is at its second or third most expensive point in history. So people are saying, “I either don’t understand the world anymore, or I don’t think that valuation matters anymore,” which is a really weird thing to say. You’re giving up the one piece of information that you know helps determine your long-term returns. You cannot describe yourself as an investor if you are going passive. You are welcome to call yourself a speculator, but you honestly can’t say you care about expected returns if you are going passive at this time.

For those standing against the tide, there are a couple of challenges. One, how much pain can you take? The U.S. has been an incredibly strong market for a number of years, so going passive is classic returns-chasing behavior. How do you manage the pain? Nothing in the precepts of being a value investor tells you about the path or the timing. It just tells you about the final destination. The light at the end of tunnel is that the more that people buy on the basis of market cap, the greater the opportunity for active managers.

You have also taken Warren Buffett to task.

All these years I have looked to Warren Buffett as a beacon of hope. Two months ago, he said that equities look cheap, relative to interest rates. It seemed like a dreadful thing to say. It might be true only if you believed there was absolutely no mean reversion—in that case you’d be looking at a 3% real return from equities, zero from bonds, and, say, minus 1% or 2% from cash. But here was a man who, using his favorite valuation indicator of market cap to gross domestic product, pointed to the tech bubble of 2000 and said it was insane. Using the same indicator, he pointed out when to buy equities in late 2008, early ’09. Here we are within a hair’s breadth of the levels in 2000, and he is saying equities are cheap. This is an unvaluelike statement, and I don’t think it’s true. There are plenty of reasons why interest rates are not related to performance—very low rates haven’t stopped a 50% decline in Japan. So I’m sticking to dead heroes now—Ben Graham and John Maynard Keynes.

You can read the full interview here (subscription required).