Just when you think that Ed Keon is a devout member of the Church of Real Assets, he says something that many true believers would consider grounds for excommunication.

First, the self-described “quant” says there is nothing investment managers of his ilk more strongly believe in than the power of diversification. A portfolio rich in variety can reduce the volatility without necessarily harming expected returns, he says, and real assets is an essential tool of diversification.

So far, so good.

Then, however, when asked which real asset he thinks will perform best during the next five years, Keon says he has always believed the best real asset is common stock.

Huh?

That is when the interviewer calls into question common stock’s validity as a real asset.

Keon — managing director and portfolio manager of QMA, a wholly owned subsidiary of Prudential headquartered in Newark, N.J. — acknowledges that most investors do