The Loss Aversion / Narrow Framing Approach to the Equity Premium Puzzle

We review a recent approach to understanding the equity premium puzzle. The key elements of this approach are loss aversion and narrow framing, two well-known features of decision-making under risk in experimental settings. In equilibrium, models that incorporate these ideas can generate a large equity premium and a low and stable risk-free rate, even when consumption growth is smooth and only weakly correlated with the stock market. Moreover, they can do so for parameter values that correspond to sensible attitudes to independent monetary gambles. We conclude by suggesting some possible directions for future research.

Prospect Theory and Asset Prices

We propose a new framework for pricing assets, derived in part from the traditional consumption-based approach, but which also incorporates two long-standing ideas in psychology: prospect theory, and evidence on how prior outcomes affect risky choice. Consistent with prospect theory, the investor in our model derives utility not only from consumption levels but also from changes in the value of his financial wealth. He is much more sensitive to reductions in wealth than to increases, the ``loss-aversion'' feature of prospect utility. Moreover consistent with experimental evidence, the utility he receives from gains and losses in wealth depends on his prior investment outcomes; prior gains cushion subsequent losses -- the so-called 'house-money' effect -- while prior losses intensify the pain of subsequent shortfalls. We study asset prices in the presence of agents with preferences of this type, and find that our model reproduces the high mean, volatility, and predictability of stock returns. The key to our results is that the agent's risk-aversion changes over time as a function of his investment performance. This makes prices much more volatile than underlying dividends and together with the investor's loss-aversion, leads to large equity premia. Our results obtain with reasonable values for all parameters.

Prospect Theory and Asset Prices

We study asset prices in an economy where investors derive direct utility not only from consumption but also from fluctuations in the value of their financial wealth. They are loss averse over these fluctuations and the degree of loss aversion depends on their prior investment performance. We find that our framework can help explain the high mean, excess volatility and predictability of stock returns, as well as their low correlation with consumption growth. The design of our model is influenced by prospect theory and by experimental evidence on how prior outcomes affect risky choice.