Platform competition and seller investment incentives

Many products and services are not sold on open platforms but on competing for-profit platforms, which charge buyers and sellers for access. What is the effect of for-profit intermediation on seller investment incentives? Since for-profit intermediaries reduce the available rents in the market, one might naively suspect that sellers have weaker investment incentives with competing for-profit platforms. However, we show that for-profit intermediation may lead to overinvestment when free access would lead to underinvestment because investment decisions affect the strength of indirect network effects and, thus, access prices. We characterize the effect of for-profit intermediation on investment incentives depending on the nature of the investment and on which side of the market singlehomes.