This paper empirically investigates the effects of stock exchange M&As on their competitors’ shareholder value. The focus first is on the 63 M&As of stock exchanges and their respective competitors in the same region during the 2000-2007 period and investigate the short-run performance (share-price responses) of these public stock exchanges. We observe that when a stock exchange is merged with another exchange, its competitor significantly lose its shareholder value. When the stock exchange is involved in a horizontal (cross-region) transaction instead of a vertical (within-region) one, its competitor loses more shareholder value. Second, we trace the stock exchanges in the MENA region and conduct a similar analysis for stock exchange M&A and alliance deals in MENA region and find that the above results still hold. We also find that when the stock exchange is involved in a deal with is a M&A instead of an alliance, its competitor loses more shareholder value.