The findings are summarized in this post in PSA blog.
In a nutshell, what is suggest is that the (effective) number of political parties is positively related to the volume of FDI inflow in developing countries. Investors are less concerned about the investment climates in developing countries (which are otherwise not very glamorous) when there are many political parties to 1) decrease the chances of reckless policy decisions and 2) channel a wide swath of public demands to the government. This figure below aptly summarizes the relationship between the number of parties (ENPP) and FDI.
Nisha Bellinger and Byunghwan Son. 2018. "Political Parties and Foreign Direct Investment Inflows among Developing Countries." Political Studies. https://doi.org/10.1177/0032321718799015. Forthcoming.
