Big deals, big returns? Don't bet on it By: MarketWatch May 18, 2010 at 00:01 AM EDT Merger Monday has returned. But don't break out the cigars and Champagne just yet, writes David Weidner. Read More >> Related Stocks: CBOE Volatility Index Macy's SAP Ag ADR Telefonica S.A. ADR Wal-Mart Stores, Inc.