In this paper, I examine the antecedents of successful IT M&As. Drawing from several theories from strategic management, I propose several hypotheses about the impact of acquiring firm’s environmental uncertainty, pairwise technology complementarity, product market proximity, and the acquiring firm’s CEO narcissism on combined firm’s post-M&A performance measured by profitability and innovation capability. Empirical results partially support my hypotheses: I find that technological complementarity is positively correlated with both post-merger profitability and innovation capability. CEO narcissism, on the hand, only impacts the profitability measure and there is an inversed U-shape relationship. I also find the positive interaction effect between CEO narcissism and technological complementarity on profitability.