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Main Authors: Wei, Jiaming, Zou, Dihan
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2512.06525
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author Wei, Jiaming
Zou, Dihan
author_facet Wei, Jiaming
Zou, Dihan
contents We study monopoly regulation under asymmetric information about costs when subsidies are infeasible. A monopolist with privately known marginal cost serves a single product market and sets a price. The regulator maximizes a weighted welfare function using unit taxes as sole policy instrument. We identify a sufficient and necessary condition for when laissez-faire is optimal. When intervention is desired, we provide simple sufficient conditions under which the optimal policy is a progressive price cap: prices below a benchmark face no tax, while higher prices are taxed at increasing and potentially prohibitive rates. This policy combines delegation at low prices with taxation at high prices, balancing access, affordability, and profitability. Our results clarify when taxes act as complements to subsidies and when they serve only as imperfect substitutes, illuminating how feasible policy instruments shape optimal regulatory design.
format Preprint
id arxiv_https___arxiv_org_abs_2512_06525
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Regulating a Monopolist without Subsidy
Wei, Jiaming
Zou, Dihan
Theoretical Economics
We study monopoly regulation under asymmetric information about costs when subsidies are infeasible. A monopolist with privately known marginal cost serves a single product market and sets a price. The regulator maximizes a weighted welfare function using unit taxes as sole policy instrument. We identify a sufficient and necessary condition for when laissez-faire is optimal. When intervention is desired, we provide simple sufficient conditions under which the optimal policy is a progressive price cap: prices below a benchmark face no tax, while higher prices are taxed at increasing and potentially prohibitive rates. This policy combines delegation at low prices with taxation at high prices, balancing access, affordability, and profitability. Our results clarify when taxes act as complements to subsidies and when they serve only as imperfect substitutes, illuminating how feasible policy instruments shape optimal regulatory design.
title Regulating a Monopolist without Subsidy
topic Theoretical Economics
url https://arxiv.org/abs/2512.06525