By SAM MAMUDI
Investors saving for retirement can find mutual funds that invest in almost any kind of asset, but they can't buy the one thing that will have the biggest impact on their nest egg: luck.
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Forget about who's the hottest fund manager, which is the best-performing fund or which sector appears to be the best bet. The biggest factor in long-term returns is how the financial markets happen to perform during the 30 or so years an investor puts money away for retirement.