In pondering why some stocks are more affected by weak markets than others I ran some data since May 1st looking at how different stocks have fared in 2011 based on the size of their institutional share base. Since May 1 the average Russell 2000 stock in my sample has fallen by 17%. Those stocks with high institutional ownership have tended to do a little better while those with low sponsorship have done a bit worse. Surprisingly the middle quintile has done the best. The average stock with 40-60% institutional ownership was only down about 12.5% in the period.