I am not saying it is an opportunity of a lifetime. . .

. . .but there is a good chance that stock markets around the world will generate some eye-catching returns over the next 10 years.

It is an easy prediction to make, based not on the future growth of global economies or the high expectations of new administrations, but on the current valuation of the stock market itself.

According to data compiled by Yale Economist Robert J. Shiller (whose exhaustive research details the inverse correlation between a stock market’s current valuations and future returns), the last time common stocks approached today’s low valuations was 20 years ago in January, 1989. Want to guess the stock market’s annualized returns over the next decade? Try 19 percent.

I am not about to predict similar returns going forward, but there is a good chance that the market will generate at least double digit returns in the coming decade. That is the good news. The bad news is that most investors will let this opportunity of a lifetime slip away, if only because of their haphazard approach to investing in the stock market.

Let’s face it, if we peak inside a typical common stock portfolio we are likely to find a random holding of stocks and mutual funds that have accumulated from your stockbroker’s (or your own) hopes of beating the stock market average. It is a strategy that is doomed to fail.

In its 2008 Quantitative Analysis of Investor Behavior, Boston-based Dalbar, Inc. found that for the 20-year period ending 2007, the average mutual fund investor switched mutual funds every four years and ended up with less than half the stock market’s average return.

To put it bluntly, investors who are intent on beating the stock market through the buying and selling of top-rated stocks and mutual funds usually end up underperforming it by a mile. Doesn’t make much sense to me.

Is a change due in your portfolio? Maybe it is time to admit to your therapist that you can’t beat the market. There has never been a better time to get rid of individual stocks and actively managed mutual funds in your account and position your holdings to take advantage of what is likely to be an opportunity of a lifetime.

Let your New Year’s resolution be one of clarity over chaos in your common stock holdings. You can easily accomplish this by building a globally diversified portfolio of low cost index funds.

Looking back at 2008 and a financial world that produced everything from mortgage meltdowns to Madoff’s scandal, one can become disillusioned with the Wall Street crowd.

Fortunately, you can ignore Wall Street, build a successful portfolio and get on with your life, all at the same time. Maybe it IS an opportunity of a lifetime. Don’t let it pass you by.