We consider a reduced form model with acquisitions and entry. There are two investors and several small non-investing firms. One investor can acquire a small firm, the other investor decides about market entry. After that all firms play an oligopoly game. We derive conditions under which increasing market concentration arises with myopic firms. We apply the framework to a Cournot model with cost synergies and a Bertrand model where acquisitions extend the product spectrum of a firm.