Short Increase Leaders: April 13 to May 15

Here are the increase leader for the past month. People who are negative on a stock will sell it short in hopes on buying it back later at a cheaper price. Large positions can lead to a "short squeeze". This happens when large numbers of short sellers are forced to buy back the stock as it rises, this cause huge buying and usually a dramatic run up in the stock. Here they are:

The number is the increase in the number of shares short (rounded):

CVS (CVS) = + 46,000,000
Valero (VLO) = + 35,000,000
Altria (MO) = +29,000,000
Advanced Micro (AMD) = + 28,000,000
Ishares Russell 2000 (IWM) = + 18,000,000
Regions Financial (RF) = + 17,000,000
Time Warner (TWX) = + 16,000,000
Constellation Brands (STZ) = + 14,000,000
Delta Airlines (DAL) = + 14,000,000
Southwest Airlines (LUV) = + 13,000,000