Major U.S. markets ended Monday's trading session mostly flat but the Nasdaq was slightly lower. The Dow Jones Industrials and S&P 500 staged a late day comeback and managed to close slightly higher. The government's announcement that pending home sales unexpectedly fell in June, down 1.1 percent, rattled the markets. Home builder stocks lost ground on the report, Lennar (LEN), KB Home (KBH) and DR Horton (DHI) each was down roughly 2 percent. Traders were initially greeted with loads of news from the deals front this morning before the bell. Dollar Tree (DLTR) is buying Family Dollar (FDO) for $8.5 billion. Both stocks ended with gains. Zillow (Z) also said it was buying its rival Trulia (TRLA). Scheduled to report on Tuesday are Merck (MRK), Pfizer (PFE) and Twitter (TWTR). TheStreet's Susannah Lee reports from Wall Street.