Everyone that's read Burton Malkiel's A Random Walk Down Wall Street learns the idea that the movement of stocks is random--they can rise or fall on any given day. Like a hitter in baseball or a shooter in basketball, players can go on "runs" that temporarily give the appearance of non-randomness. Similarly, stocks can do the same, and for a period of time violate the random walk. This is currently the case, and has in fact, been the case all year.
We measure the number of days a stock has been up and down over the previous 88 trading days (4 months). A perfectly random walk would have a stock up 50% of the says and down 50% of the days. We can also perform the exercise on stock indices. Currently, using the S&P 500 index, stocks have been up 66% of the trailing 88 days. Moreover, the percent of days up has been above 50% all year long, which is a first since the Lehman induced financial crisis of 2008.
This looks less like a random walk than a manufactured sprint, engineered by massive amounts of quantitative easing. In sports, the payback from a "run" is a "slump".