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Rethinking Modern Portfolio Theory

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Are we all doing it wrong — or is the theory in need of updating and repair?

I think MPT died 30 years ago,” says Jeffrey Saut, chief investment strategist at Raymond James. “If the theory were correct, Warren Buffett, Peter Lynch and Paul Tudor Jones wouldn’t have their track records.” He says that although 60% of Lynch’s trades resulted in losses, he could manage downside risk precisely because he wasn’t tied to a strategic asset allocation. “Asset allocation-and just about any other model-works in a bull market,” Saut scoffs. “But the driver of returns in a bear or range-bound market is stock selection and risk management.”

By Joan Warner
February 1, 2010
www.bankinvestmentconsultant.com

So far, no other single method has knocked the Modern Portfolio Theory off its perch as a coherent way of structuring portfolios and pricing assets. But more and more practitioners believe the theory doesn’t deal adequately with today’s world.

Poor Harry Markowitz. Every time investors get whipped in the financial markets, they take it out on his Modern Portfolio Theory (MPT).

Never mind that the groundbreaking concept has governed investment discipline for more than 40 years and that Markowitz won a Nobel Prize for it in 1990. Its central tenet-that diversification mitigates portfolio risk-seemed to collapse in 2008 when the bear market left no asset class unmauled. Only Treasuries provided a haven, and according to MPT, Treasuries don’t even count. They’re just the risk-free baseline at the bottom of the return axis. If you had furious clients asking what the hell happened to your age-appropriate asset allocation strategy, you weren’t alone.

Investors don’t kick Markowitz only when they’re down. MPT also came under gleeful attack during the technology boom of the late 1990s, when “risk” was a dirty word. What sense does it make to diversify out of an asset class that’s returning 30%? Plenty, of course-but try telling clients to keep a little money in cash during a raging bull market. 

- continued at-  http://www.bankinvestmentconsultant.com/bic_issues/2010_2/rethinking-modern-portfolio-theory-2665530-1.html

Why does MPT look so good on paper, yet fail so spectacularly every few years?