Stock Valuation and Learning about Profitability
提出一个简单方法，在投资者逐步了解公司平均盈利能力的过程中为股票估值。研究发现，市场账面比随盈利能力不确定性上升而增加，尤其对不派息公司；随着公司年龄增长，该比率因学习效应而下降。实证支持这些预测，并发现年轻公司和不派息公司的回报波动更大。
Abstract We develop a simple approach to valuing stocks in the presence of learning about average profitability. The market‐to‐book ratio (M/B) increases with uncertainty about average profitability, especially for firms that pay no dividends. M/B is predicted to decline over a firm's lifetime due to learning, with steeper decline when the firm is young. These predictions are confirmed empirically. Data also support the predictions that younger stocks and stocks that pay no dividends have more volatile returns. Firm profitability has become more volatile recently, helping explain the puzzling increase in average idiosyncratic return volatility observed over the past few decades.