A Stock Market sell off may be about to begin which could take the Index lower  for the full year. These six reasons demonstrate why one of the most impressive stock market runs may have ended:

1. Markets can’t rise all the time. This probably is obvious to most people. A significant is what a market requires to go higher for a market which has more than doubled in two years. Recent economic news shows that support to be lacking. The S&P has risen to more than double from 683 in March 2009 to almost 1,400 two months ago.

2. Corporate earnings have been pressured by an economic slowdown and margin drops. Many companies in the retail, transportation and manufacturing sectors counted on low commodities prices back in 2009 and 2010 to help profits. That help is gone. Oil has rallied from below $50 in mid-2009 to almost $100 recently. The price is down from $110, but it is still historically high. Prices on cotton and many agricultural commodities have also risen in the same period. The result: The cost of making and moving goods is higher, and margins on items like clothing have dropped.

3. Consumer sentiment has faltered. Recent data from from the Conference Board said “Consumer Confidence Index, which had declined in May, decreased again in June. The Index now stands at 58.5 (1985=100), down from 61.7 in May.” Many retailers have posted slow same-store sales. Activity at the world’s largest retailer, Walmart (WMT), has been down on a same store basis for its U.S. operations.