Abstract Entrepreneurs and venture capitalists are concerned about investors’ beliefs in asset markets because these beliefs shape the value of a potential IPO and the possibility to expand. Investors’ beliefs, on the other hand, can be influenced by start-up activity insofar as the latter contains valuable information about eventual profitability. This two-way feedback is shown to generate excessive, non-fundamental, waves in start-up activity, IPOs, and asset prices. Policies that “lean against the wind” can improve welfare, without requiring an informational advantage by the government.