This article examines the relationship between electoral volatility and political finance regulation in Colombia. The author argues that recent political finance reforms in this country (e.g. changes in regulation of campaign donations, campaign spending, and public funding provisions) are strategic responses to high electoral volatility. Recent reforms of political financing in Colombia have turned political parties into cartel parties that exclude new challengers from electoral competition and are increasingly dependent on public subsidies. Using data on political finance regulations and electoral volatility between 1990 and 2015, this article provides empirical evidence that increasing electoral volatility makes political campaigning more expensive and provides strong incentives for politicians to prevent new parties from entering the electoral arena, limits their access to private donations, and makes more public resources available for dominant parties.