My Fibre or Your Fibre? Cooperative Investment, Uncertainty and Access

We investigate cooperative investment in a new infrastructure and how it interacts with access obligations and demand uncertainty. Co-investment only increases total coverage if service differentiation and/or cost savings from joint investment, in particular due to high uncertainty, are high. Mandated access reduces incentives for co-investment not only through lower returns but also by creating the option to ask for access instead. Voluntary access provision increases infrastructure coverage but reduces social welfare by softening competition.