Bubble Necessity Theorem

• 成果类型: Article
• 署名作者: Hirano, Tomohiro; Toda, Alexis Akira
• 署名单位: University of London; Royal Holloway University London; Emory University
• 刊物名称: JOURNAL OF POLITICAL ECONOMY
• ISSN/ISSBN: 0022-3808
• DOI: 10.1086/732528
• 发表日期: 2025
• 页码: 111-145
• 关键词: OVERLAPPING-GENERATIONS MODEL; PURE EXCHANGE; asset; equilibrium; liquidity; constraints; economies; EXISTENCE; POLICY; debt

摘要

Asset price bubbles are situations where asset prices exceed the fundamental values defined by the present value of dividends. This paper presents a conceptually new perspective: the necessity of bubbles. We establish the bubble necessity theorem in a plausible general class of economic models: with faster long-run economic growth (G) than dividend growth (Gd) and counterfactual long-run autarky interest rate (R) below dividend growth, all equilibria are bubbly with nonnegligible bubble sizes relative to the economy. This bubble necessity condition naturally arises in economies with sufficiently strong savings motives and multiple factors or sectors with uneven productivity growth.