Since the market began its recovery following the 2008 financial crisis, a number of trends have dominated the landscape. Many of them have gone on way longer than expected, and have scaled heights never seen before. Some looked to be on their last legs two or three years ago, but are still going strong. They're the Rolling Stones of investing.

To make sense of what's going on in the economy and capital markets, I separated these trends into two lists – sustainable and unsustainable. In other words, which ones are early in the concert and which are on their second encore.

Running on Empty

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Time On My Side

The trends on the other side of the page have also been going on for a while, but in my view, are still in their early days.

Both Sides, Now

Beyond sparking debate, this simple categorization provides a useful check and balance for investors. Is your portfolio stacked heavily toward the unsustainables? Are there lots of commodities and no health care? Does it rely on the indebted Canadian consumer and have little exposure to China and India's emerging middle class? And, as most portfolios are, is it strictly designed for declining interest rates and easy credit?

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A well-diversified portfolio should be represented on both sides of the ledger. Otherwise, you can't get no satisfaction.