ADT (about to be spun off from Tyco) and Pentair (PNR) will replace Lexmark (LXK) and DeVry (DV) in the S&P 500 as of Sep. 28's close. Lexmark and DeVry will be moved over to the S&P MidCap 400, and RadioShack (RSH) and Pentair kicked out to make room. PNR +1.6% AH. LXK -1.2%. DV -2.6%. RSH -2.6%.