Two Charts That Show This Bull Market Is Truly Historic

If you hear music in the air, particularly from the direction of the financial district, that's because the six-year anniversary of our current bull market has arrived.

According to the S&P, this particular run has lasted 2,191 days, the fifth longest since 1921, only surpassed by a 3,452 day stretch from October, 1990 through March, 2000; a 2959 day period from August 1921 to September, 1929; a 2067 day stretch from June, 1949 to August, 1956; and 2248 day run between October, 1974 and November, 1980.

But while today's bull market might rank fifth overall, it's even more impressive when compared to similar economic recoveries. The six-year rally following the financial crisis is topped by only by the recovery following World War II (2,607 days) and the 1919 deflation (2,959 days).

And when it comes to price gains during the first six-years of a recovery, the current market is second to none. Between March 9, 2009 and March 9, 2015, the S&P 500 has increased by 202%. The only other market run that comes close is the postwar expansion, where the S&P returned 192% in the same time period.

The bad news? Valuations now look high.

As of February, the Shiller price-to-earnings ratio, which measures the S&P 500's price against the average of the past 10 years of earnings, was nearly 28. That's almost twice as high as the P/E six years into the "Great Bull" market of the 1980s and 1990s. That's lead many commentators to speculate about whether the market is overvalued and due for a correction.

Of course, the Shiller P/E climbed above 40 by end of the Great Bull in 2000—so it's not much of a guide to when the market will turn. But even if you aren't trying to time the market, high valuations do suggest that future long-term returns may be comparatively muted. After all, a high P/E means each dollar you spend on stocks is now buying a smaller pile of earnings.

All data from Money's Investor's Guide 2015 by Penelope Wang with Kara Brandeisky.