We consider a repeated duopoly game where each firm chooses its investment in quality, and realized quality is a noisy indicator of the firm's investment. We derive reputation equilibria, whereby consumers `discipline' a firm by switching to its rival in case its realized quality is too low. The model predicts that firms with good reputation charge a higher price, sell a bigger quantity and have a higher stock-market capitalization. Every so often, the market is subjected to turnover, whereby the highquality / good reputation firm loses market share, lowers its price and its capitalization suffers, while its rival gains market share, raises its price and enjoys increased capitalization. We examine properties of reputation equilibria. In particular, we show that the equilibrium is not efficient or nearly efficient even as the discount factor goes to 1.