Over the past eight years (2009-2016), the stock market has suffered a pullback that bottomed in the summer each year (though it didn’t necessarily start in the summer). For summer, we used the official designation: usually June 21 to Sept. 21 or 22. Let’s look at the summer lows through the lens of the Nasdaq.
In 2016, the summer low came early, June 27, and represented an 8.2% pullback from the previous high.
In 2015, the summer nadir arrived Aug. 24. The pullback was 18%, thanks to the flash crash.
In 2014, the summer low was pegged Aug. 7. The pullback could barely be called a pullback — down 3.6%.
In 2013, the summer low came early, June 24. The pullback was 6.7%.
In 2012, the summer low also was early, June 28. The pullback was 10.1%.
In 2011, the summer low appeared Aug. 9. The pullback was 19%.
In 2010, the summer low was on July 1. The pullback was 18.7%.
In 2009, the summer low rolled in July 8. The pullback was 8.1%.
The median pullback in these eight years was 8% to 10%. The average pullback was 11.5%.

（from IBD）