An increase means people are betting against the stock, a decrease means those who were betting against are getting out of those positions. Notice the short covering in Wells Fargo and Wachovia..
INCREASES- number of shares
Washington Mutual (WM)= +12,483,000
EMC (EMC)= +11,205,000
Target (TGT)= +5,720,000
Pulte Homes (PHM)= +5,392,000
Beazer Homes (BZH)= +5,209,000
Mylan (MYL)= +5,001,000
DECREASES- number of shares
Wells Fargo (WFC)= -9.180,000
Wachovia (WB)= -8,394,000
Commerce Bank (CBH) = -8,002,000
Express Jet (XJT)= -7,409,000
McDonalds (MCD)= -6,569,000