Asset returns, it turns out, do not follow the Capital Asset Pricing Model, and are somewhat predictable over time. I survey and interpret the large body of recent work that adapts traditional portfolio theory to answer, what should an investor do about these new facts in finance? I survey the...

If stocks go up, investors may want to rebalance their portfolios. But investors cannot all rebalance. Expected returns may need to change so that the average investor is still happy to hold the market portfolio despite its changed composition. In this way, simple market clearing can give rise...

We present a consumption-based model that explains the procyclical variation of stock prices, the long-horizon predictability of excess stock returns, and the countercyclical variation of stock market volatility. Our model has an i.i.d. consumption growth driving process, and adds a slow-moving...

Mean-variance portfolio theory can apply to the streams of payoffs such as dividends following an initial investment, in place of one-period returns. This description is especially useful when returns are not independent over time and investors have non-marketed income. Investors hedge their...