Rite Aid (RAD) is seeing relative strength and call volume is picking up after UBS said CVS, Wal-green’s (WAG), or Wal-mart (WMT) could have interest in RAD. Shares are up 20 cents to $1.59 and 1495 Jul 2.5 calls traded (75 percent Ask). Another 745 Apr 2.5 calls changed hands (88 percent Ask).