See How the Dow Raced to 20,000

It finally happened: Dow 20,000. The iconic Dow Jones industrial average reached the momentous milestone when the market opened today. Thanks to a vigorous post-election stock market rally, the index has been flirting with the 20K mark since mid-December (getting as close as 19,999.63 on Jan. 6). Adding to the excitement is the fact that the stock index—which tracks the value of 30 large U.S. companies—just crossed 19,000 for the first time in November, right before Thanksgiving. But investors should be careful about celebrating the speed with which the venerable index got to 20,000: As this graphic shows, the last (and only) time the Dow jumped 1,000 points this fast, in 1999, it took 7½ years to level up again.