This article studies the impact of regulatory uncertainty on an incumbent’s incentives to undertake the socially optimal investments in NGA networks. Thus, aregulatory non - commitment setting in which the regulator sets the access price after the deployment of the NGA network is used. In particular, it is assumed that the regulator sets the access price at the marginal cost of providing the access with some probability and gives an access markup, which equals the average cost of the investments, with the complementary probability. It is found that when the slope of the marginal investment cost function is not particularly steep in relation to the impact of investments on demand, the incumbent underinvests compared to the socially optimal investment level. On the contrary, in a more realistic case when the impact of investments on demand is low in relation to the slope of the marginal investment costfunction, the incumbent may overinvest or underinvest depending on the probability of incorporating an access markup into the access price.
