We examined multimarket trading in the stock and option markets during merger announcement and successful and failed completion. Using contemporary intraday stock and options data, we observed alternate call buying and stock selling for acquirer stock in cash mergers, call writing and stock selling, followed by put buying for acquirer stock in stock mergers at merger announcement. For successful completions, stock selling dominated for cash acquirers and put buying for stock acquirers. Deal failure was accompanied by initial put buying, followed by call writing and stock selling on target stock. Signalling between markets and the alternation of informed trading between markets was inferred.