Stock Market Mean Reversion And Portfolio Choice Over The Life Cycle

We solve for optimal consumption and portfolio choice in a life-cycle model with short-sales and borrowing constraints, undiversifiable labor income risk and a predictable, time-varying, equity premium and show that the investor pursues aggressive market timing strategies. Importantly, in the presence of stock market predictability, the model suggests that the conventional financial advice of reducing stock market exposure as retirement approaches is correct on average, but ignoring changing market information can lead to substantial welfare losses. Therefore, enhanced target-date funds (ETDFs) that condition on expected equity premia increase welfare relative to target-date funds (TDFs). Out-of-sample analysis supports these conclusions.

Academic finance has had a remarkable impact on many financial services. Yet long-term investors have received curiously little guidance from academic financial economists. Mean-variance analysis, developed almost fifty years ago, has provided a basic paradigm for portfolio choice. This approach usefully emphasizes the ability of diversification to reduce risk, but it ignores several critically important factors. Most notably, the analysis is static; it assumes that investors care only about risks to wealth one period ahead. However, many investors—-both individuals and institutions such as charitable foundations or universities—-seek to finance a stream of consumption over a long lifetime. In addition, mean-variance analysis treats financial wealth in isolation from income. Long-term investors typically receive a stream of income and use it, along with financial wealth, to support their consumption. At the theoretical level, it is well understood that the solution to a long-term portfolio choice problem can be very different from the solution to a short-term problem. Long-term investors care about intertemporal shocks to investment opportunities and labor income as well as shocks to wealth itself, and they may use financial assets to hedge their intertemporal risks. This should be important in practice because there is a great deal of empirical evidence that investment opportunities—-both interest rates and risk premia on bonds and stocks—-vary through time. Yet this insight has had little influence on investment practice because it is hard to solve for optimal portfolios in intertemporal models. This book seeks to develop the intertemporal approach into an empirical paradigm that can compete with the standard mean-variance analysis. The book shows that long-term inflation-indexed bonds are the riskless asset for long-term investors, it explains the conditions under which stocks are safer assets for long-term than for short-term investors, and it shows how labor income influences portfolio choice. These results shed new light on the rules of thumb used by financial planners. The book explains recent advances in both analytical and numerical methods, and shows how they can be used to understand the portfolio choice problems of long-term investors.

We study portfolio choice when labor income and dividends are cointegrated. Economically plausible calibrations suggest young investors should take substantial short positions in the stock market. Because of cointegration the young agent's human capital electively becomes stock-like. However, for older agents with shorter times - to - retirement, cointegration does not have sufficient time to act, and thus their human capital becomes more bond-like. Together, these exects create hump - shaped life - cycle portfolio holdings, consistent with empirical observation. These results hold even when asset return predictability is accounted for.

Diversification provides a well-known way of getting something close to a free lunch: by spreading money across different kinds of investments, investors can earn the same return with lower risk (or a much higher return for the same amount of risk). This strategy, introduced nearly fifty years ago, led to such strategies as index funds. What if we were all missing out on another free lunch that’s right under our noses? InLifecycle Investing, Barry Nalebuff and Ian Ayres-two of the most innovative thinkers in business, law, and economics-have developed tools that will allow nearly any investor to diversify their portfolios over time. By using leveraging when young-a controversial idea that sparked hate mail when the authors first floated it in the pages ofForbes-investors of all stripes, from those just starting to plan to those getting ready to retire, can substantially reduce overall risk while improving their returns. InLifecycle Investing, readers will learn How to figure out the level of exposure and leverage that’s right foryou How the Lifecycle Investing strategy would have performed in the historical market Why it will work even if everyone does it Whennotto adopt the Lifecycle Investing strategy Clearly written and backed by rigorous research,Lifecycle Investingpresents a simple but radical idea that will shake up how we think about retirement investing even as it provides a healthier nest egg in a nicely feathered nest.

This paper solves numerically for the optimal consumption and portfolio choice of a long-horizon investor facing short-sales and borrowing constraints, undiversifiable labor income risk and a predictable time varying equity premium. The investor pursues aggressive market timing strategies; a speculative increase in savings arises when stock returns are expected to be high and conversely when future returns are expected to be low. Positive correlation between permanent earnings shocks and stock return innovations generates a substantial hedging demand for the riskless asset for risk averse investors. Hedging demands arising from the correlation of permanent earnings shocks and the factor innovation and from the correlation between the factor innovation and the stock market shock are evaluated and are found to be small in magnitude. Conversely, asset demand changes that arise from relaxing the liquidity constraints are substantial.

Do households holding risky financial securities tend to invest in the stock market, buying at the top and selling at the bottom? Do they reduce their risk exposure with age and especially when approaching retirement? We answer these questions using data on retirement savings contracts from a large French insurer over the period 2002 to 2009. Subscribers can invest their savings in two types of investment vehicles: a euro fund composed primarily of money market securities with almost no risk, and unit-linked funds representing UCITS shares invested in risky securities. We show that the share of capital invested in unit-linked funds is sensitive to market conditions, but mainly at the date of subscription. Once the initial share has been selected, inertia of portfolio choice is observed as investors rarely revise their position subsequently. We observe a steep procyclicality of investment choices which can be explained by extrapolation of recent market performance. New subscribers buy risky assets when the stock market rises and stop buying them when it drops. This leads them to hold a minimum share of risky assets in 2004, a beginning of a 4-year rising phase and a maximum share in 2008 at the beginning of a fall market.We also find that the risky share declines with age once time effects are controlled for and cohort effects are excluded. The age profile also declines in the reverse configuration (taking into account cohort effects and excluding time effects) but the decline is less pronounced. After a discussion of the plausibility of the different effects, we estimate a probability of unit-linked detention which decreases by about 12 percentage points with age between ages 40 and 60, and a conditional equity share which decreases by about 6 percentage points with age between 40 and 60 years. This decrease is too small to bring the invested share to zero when approaching retirement.

This paper solves numerically the intertemporal consumption and portfolio choice problem of an infinitely-lived investor who faces a time-varying equity premium. The solutions we obtain are very similar to the approximate analytical solutions of Campbell and Viceira (1999), except at the upper extreme of the state space where both the numerical consumption and portfolio rules flatten out. We also consider a constrained version of the problem in which the investor faces borrowing and short-sales constraints. These constraints bind when the equity premium moves away from its mean in either direction, and are particularly severe for risk-tolerant investors. The optimal constrained portfolio rules are similar but not identical to the optimal unconstrained rules with the constraints imposed. The portfolio constraints also affect the optimal consumption policy.