This Saturday marks the third anniversary of the low-water mark in the stock market meltdown during the financial crisis. As painful as that period was, it was definitely a learning experience -- and if you've been fortunate, you've probably learned a lot from the last three years since then as well.

Where we've been
Three years ago, the financial system seemed to be on the brink of collapse. Everything from banks and insurance companies to automakers and money market mutual funds had required some form of financial bailout or guarantee to try to get the mechanisms of finance working smoothly again.

Meanwhile, a stock market that was already bemoaning the loss of half a decade's worth of gains couldn't figure out where the bottom of the market was. With gargantuan losses from the financial sector, valuation measures for the broad market like P/E ratios became virtually meaningless, and many foresaw further declines even from Dow 6,500.

Of course, with perfect hindsight, we know that was overly pessimistic. Now, the broad market has doubled from its 2009 lows. Many individual stocks have done far better than that, having dodged what could have been death blows during the financial crisis. Yet even now, many individual investors have no confidence in the stock market, seeing it as a rigged game and another example of Wall Street domination of the financial system.

Where we're going
No one knows what'll happen next for stocks. Some believe that after having come so far so quickly, we're long overdue for a correction that will take most stocks lower. Others point to rising corporate earnings as a sign that even after the big run, valuations are still attractive enough to support further gains.

But the true lessons of the market meltdown and the recovery that followed it come from one basic fact: Markets are always in flux, and you have to be flexible in order to roll with the punches and succeed in the long run.

The tenacity of markets
One lesson that's come home to just about everyone is that markets can keep going up or down far longer than you'd think possible. Like many, I've long been convinced that interest rates on bonds are too low and that a future increase is inevitable. When that happens, those who've bought long-term bonds at low rates will suffer big capital losses.

Yet low rates persist, and it looks like they'll be around for quite a while to come. That's great news for some industries. Mortgage REITs Annaly Capital (NYSE: NLY) and American Capital Agency (Nasdaq: AGNC) are in a better position to thrive as a result of low rates, although they also face challenges from ongoing pressures in the mortgage-loan market. But for savers and those who depend on interest income from their portfolios, low rates have forced them into the uncomfortable position of deciding which type of risk to take on to enhance their returns.

History repeats
No matter how many times crazy behavior smacks down a group of investors, people seem doomed to repeat it.

You'd think that the Internet boom and bust of the late 1990s and early 2000s would have taught everyone about the pitfalls of mania-based investing. Yet in recent years, first Chinese Internet stocks and then social media stocks have exhibited some of the same signs of froth.

As with the original Internet boom, there are legitimate players. Among Chinese Internet stocks, Baidu (Nasdaq: BIDU) has established itself as a force to be reckoned with, not just within China but internationally as well. In social media, LinkedIn (NYSE: LNKD) may have a ridiculously high valuation, but at least it's profitable -- as is Facebook.

But as with the insert-name-here-dot-com companies more than a decade ago, a host of follow-on offerings appear doomed from the start. Renren (NYSE: RENN) has lost nearly three-quarters of its value from its IPO, and while revenue growth has been strong, figuring out how to generate profit will be an ongoing challenge for the company. Among narrowly focused social media companies, a few will succeed, but many more will fail.

What about you?
Those are just two of the lessons I've learned from the markets since 2009. But what about you? Share your experience by leaving a comment below and tell us what you've learned from the market's recovery.

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