In my point of view when this happen both companies will have some dificulties do manager this change. For example, the acquiring company generally bigger than startup companie will have a lot of rules, sistem and governance do to the things, and the other side, the target company (in this case, a startup) probably don’t have many rules and compliance, and this help him to do the things faster. This example, generally is the cause that why M&As fails, even if you keep the leadership, because the excess of rules, compliance and slowness that the target companie wasn’t used to, it is difficult to stay competitive.
