While some economists are skeptical about the economic benefits of hosting the Olympic Games, emphasizing that such "mega-events" often have large costs, hosting (or even bidding for) the Olympics appears to increase the host country's exports, as the host or candidate country sends a signal about trade openness when bidding to host the Games.[3] Moreover, research suggests that hosting the Summer Olympics has a strong positive effect on the philanthropic contributions of corporations headquartered in the host city, which seems to benefit the local nonprofit sector. This positive effect begins in the years leading up to the Games and might persist for several years afterwards, although not permanently. This finding suggests that hosting the Olympics might create opportunities for cities to influence local corporations in ways that benefit the local nonprofit sector and civil society.[4] The Games have also had significant negative effects on host communities; for example, the Centre on Housing Rights and Evictions reports that the Olympics displaced more than two million people over two decades, often disproportionately affecting disadvantaged groups.[5]