We analyze how the proliferation of short-term rentals (STRs) affects firm survival, performance, and entry in two European cities with high STR density. Using administrative firm-level accounting data, a shift-share instrument, and an event-study design, we find that STR growth increases exit rates among underperforming firms, while surviving firms experience relative gains in sales and profits, with minimal effects on employment or investment. Operational costs, particularly rents and liabilities, also rise. STR expansion stimulates entrepreneurship, though new entrants face higher costs and lower initial profitability. These findings underscore the nuanced impacts of tourism-driven demand shocks on urban economic ecosystems.