One concern about regulated monopolies entering unregulated vertically-related markets is that they will discriminate against competitors of their unregulated affiliates. However, prohibiting regulated monopolies from offering related goods may preclude production by the most efficient provider....

Well-established economic principles show that regulated monopolies may have an incentive to act discriminatorily against rivals of their unregulated affiliates. This paper discusses some recent empirical evidence regarding discrimination in telecommunications. Specifically, it surveys anecdotal...