I test the impact of information acquisition (proxied by SEC EDGAR web traffic) on market informativeness about deal value creation in mergers and acquisitions (M&As). Information acquisition about merging firms, industry rivals, and supply-chain firms enhance short-term market reactions informativeness about long-term merger operating synergies. The effects are more pronounced among M&As with more sophisticated investors, new information, and pre-merger information asymmetry. Furthermore, information acquisition about merging firms improves the market’s assessment of financial synergies. In addition, non-deal related firms with more downloads experience an increase in subsequent takeover probability. The evidence from difference-in-differences analysis and instrumental approach analysis suggests potential casual effects of information acquisition on market reaction informativeness. Overall, this paper demonstrates that information acquisition improves the market’s assessment of value creation in M&As.