The paper examines recent reforms in the rules of campaign financing and political parties in Argentina, Brazil, Chile and Uruguay. The objective is to identify the effects on party fragmentation. In particularly the main interest is to observe if the reforms have benefited the big parties with greater access to resources, both public and private. The rules of redistributions of resources can favor a concentration of party representation or a dispersion of political power. In the first section, the paper discusses that the private funding. It is intended to identify changes in the criteria for participation in the market and the impact of this intervention. Regarding the share of public funding, the second section of the paper, analyzes the rules on direct costing, through the transfer of funds to parties and / or candidates. In this case, the criteria for redistribution of public money shapes the profile of allocation of resources, either equality or proportionality to the weight of parties representation.The last section discusses the reforms relating to access to electronic media (radio and television), where we observe the role of the State and private sector participation. It is argued that the pattern of funding and criteria for regulating access to the media campaigns are factors that can strengthen more competitive party as a consequence of the proportional distribution resources, with effectsOtros autores on party fragmentation.