The 7 new rules of financial security

Old thinking: A diversified portfolio lowers your risk.
New rule: Diversification won't always save you - and you need more of it than you think.

Diversification hasn't stopped you from getting hurt in this downturn. Both U.S. and foreign stocks are deep in the red. Holding bonds did cushion your losses, but most kinds of bonds still declined. What happened?

Jeremy Grantham, chief investment strategist at GMO, observed back in 2007 that we had a bubble not just in one or two kinds of assets, but in risk. Investors around the world were so confident, and so hungry for even a little extra return, that they were throwing money at anything that might deliver. Now that the risk bubble has burst, all those investors want now is the safety of U.S. Treasuries. So everything has moved roughly in sync, both up and down, for a few years.

Bear in mind, though, that these times are, to say the least, unusual. Over a longer period - as little as a decade - diversification still looks effective. While large U.S. stocks are down the past 10 years, U.S. corporate bonds earned 4.6% a year for the same period.

But in a global economy where money moves quickly, you have to work harder at diversification than before.

What to do: To ensure you are diversified, you don't have to go out and buy 16 new mutual funds. First, look under the hood of the funds you have to see if you already own some of those assets. An easy way to do so is to plug your holdings into Morningstar.com's Instant X-Ray tool. And buy funds that kill two birds with one stone. The T. Rowe Price International Bond fund, for example, invests up to 20% of its assets in emerging markets and the rest in developed countries. Put that together with a high-yield fund and a broad U.S. bond fund, and you'll own most of the bond universe.

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