NEW YORK ( TheStreet) -- A recent debate between Wharton Professor Jeremy Siegel and Pimco founder Bill Gross has called into question the "historic" outperformance of stocks compared to every other asset class, and the ability of stocks to keep outperforming in the next decade.Gross is the leader of one of the largest families of asset funds at Pimco. In a nutshell the so-called "Bond King" wrote in his
But here's where Gross (and British investor Jeremy Grantham for another) might be right: The continuing returns of stocks that we have enjoyed for the past two years may have just about run out. Two years ago the spread between the yields of stocks and bonds was almost three times what it is now, with little more that the Fed can do to pressure Treasury yields down further. In the next several years, I think the master at Pimco will be right -- returns on stocks will not be the "historic" average of 6.6% often quoted by Siegel and others; it will be far less and not particularly impressive, especially for investors who need yield to retire and live on. Now is the time to start looking over your portfolio and find assets that can continue to provide yield, even if their prospects for growth aren't their deepest calling card. While I want to get investors thinking about other investments than traditional "growth" stocks for the next several years, I'm not about to give ultimate direction on where that value might lie. It could be in farm land or other real estate, perhaps in some hedge basket of commodities or perhaps a new emerging-market fund. I am an energy guy, so I can give you some ideas in that space. I have continued to support the idea of dividend multi-national integrated energy companies as a core holding, particularly Exxon Mobil ( XOM) and Royal Dutch Shell ( RDS.A), both of which are making what I consider the right long-term moves in energy and both of which have unassailable dividends and stock buyback programs. Another place to look is energy trusts and master limited partnerships. These are more risky, but with six or more of them in a portfolio you can minimize some of that risk and still yield a comfortable 5% or more. One secondary in the space today stands out as an opportunity -- MarkWest Energy Partners ( MWE) , yielding almost 6% based upon its current stock price. At the time of publication the author had positions in XOM, RDS.A and MWE. This article is commentary by an independent contributor, separate from TheStreet's regular news coverage.