Capital asset pricing in an overlapping generations model

This paper attempts to contribute to two rapidly growing branches in economic theory: asset pricing and “overlapping generations” models. The model is formulated and it is shown that equilibrium prices exist, and some of their properties are discussed. Then the model is applied to an asymmetric information environment to see if randomness in the number of informed agents could confuse the uninformed. Surprisingly, it could not.     

Asset bubbles in an overlapping generations model with endogenous labor supply

This paper examines the effects of asset bubbles in an overlapping generations model with endogenous labor supply. We show analytically that asset bubbles can lead to an expansion in steady-state capital, investment, employment and output under certain conditions.     

Gains from trade with overlapping generations

Summary This paper examines the welfare effects of international trade in a context of overlapping generations. It shows that, for a single trading country, uncompensated free trade may be Pareto inferior to autarky. However, for each government there are compensation schemes which guarantee welfare improvements for all local individuals when free trade is allowed, or when for a small open economy the terms of trade improve or the number of tradable goods increases, or when a customs union is formed.We acknowledge with gratitude the probing comments of Henry Y. Wan, Jr. and two anonymous referees.     

Asset pricing with adaptive learning

We study the extent to which self-referential adaptive learning can explain stylized asset pricing facts in a general equilibrium framework. In particular, we analyze the effects of recursive least squares and constant gain algorithms in a production economy and a Lucas type endowment economy. We find that (a) recursive least squares learning has almost no effects on asset price behavior, since the algorithm converges relatively fast to rational expectations, (b) constant gain learning may contribute towards explaining the stock price and return volatility as well as the predictability of excess returns in the endowment economy but (c) in the production economy the effects of constant gain learning are mitigated by the persistence induced by capital accumulation. We conclude that in the context of these two commonly used models, standard linear self-referential learning does not resolve the asset pricing puzzles observed in the data.     

Asset pricing and downside risk in the Australian share market

As downside risk has been identified as a separate risk exposure to investors, we investigate whether downside beta and co-skewness exposure impact on the return to investors in Australian equities. Although considered as a developed market, the Australian Securities Exchange merits separate investigation, as it is small and concentrated on some sectors, when compared with the major developed markets. As realized returns are a proxy for expected returns, we separately examine conditional returns in upturn and downturn periods. We find that both downside risks are separately priced by investors, and that our results are unaffected by the inclusion of a range of company characteristics. We subsequently confirm that returns to each downside risk are not related. In robustness tests, we conclude that the return to downside risk cannot be explained by a size, a value, or a momentum premium. Although it also has explanatory power, the inclusion of a leverage factor also does not reduce the explanatory power of downside risk.     

Asset pricing and institutional investors with disagreements

We develop a dynamic asset pricing model with two institutional investors who have benchmark incentives and who disagree about the underlying economy. We derive semi-closed form expressions for all equilibrium quantities. We find that the benchmark stock price increases and the non-benchmark stock price decreases with the benchmark incentives. Furthermore, each stock price decreases with its own disagreement and increases with the other stock disagreement. We also show that there is a positive relationship between the co-movement of the stocks and the benchmark incentives, but that this co-movement is negative with the disagreements, owing to the endogenous risk-sharing mechanisms. Moreover, we find that, when one stock disagreement increases, the optimistic institutional investor always takes positions on this stock by shorting the other stock and the bond in order to hedge against the risk of market changes, in line with the pessimistic investor's beliefs.     

On stationary overlapping generations models

Consider a stationary consumption–loan economy with fixed amount of fiat money. We show that although the economy is stationary if the number of goods and the number of ‘types’ of consumers are larger than one, there might be no Pareto optimal stationary competitive equilibrium.     

A two-sector overlapping generations model with heterogeneous capital

Summary. This paper characterizes the existence and stability properties of steady state solutions as well as the nature of transition paths of a two-sector growth model with heterogeneous capital. It compares the properties of a Cobb-Douglas–Leontief economy with heterogeneous capital with the properties of the same economy with homogeneous capital. The model with heterogeneous capital reveals a set of characteristics different to those of the model with homogeneous capital. These include the saddle-path stability of the non-trivial steady state as well as the possibility of overshooting and in contrast to the homogeneous capital case, the possibility of damped oscillations along the transition path for realistic parameter values. Received: September 21, 2001; revised version: November 21, 2002 RID="*" ID="*" We thank Costas Azariadis, and Laurie Conway for helpful comments on a previous draft. The paper has substantially benefited from the feedback of an anonymous referee. Correspondence to: R. Wendner     

Competitive equilibria in overlapping generations Experiments

Summary The paper presents the results of four overlapping generations experiments performed at the California Institute of Technology. Overlapping generations markets were created in which each agent had a two period life span. With the exception of the first period, there were eight agents trading in each period; four buyers (two young and two old) and four sellers (two young and two old). Parameters were selected so that a small set of equilibria existed. The markets were open for twenty-nine periods with a demand shift occurring at the fifteenth and sixteenth periods.This work provides a method of computing all competitive equilibria for a class of environments—called the opposing shift environments. The main conclusion of the experiments is that the experimental price data converge to near the stationary portions of the competitive equilibria. Demographic dynamics are also explored as part of the price adjustment process. Dynamic features found in non-overlapping environments are also observed in the overlapping generations case.We thank E. J. Nanale, a Caltech undergraduate student, who helped design and conduct the experiments. Special thanks are due to Hsing Yang Lee for his help in adapting the Multiple Unit Double Auction Program to accomodate the overlapping generations environment and for his help with the data processing. We also thank David Grether who found a serious problem with the statistical analysis in an early draft. The research assistance of Kay-Yut Chen was also very valuable to the completion of this work. The comments and suggestions of P. Rangazas were very helpful. The research of the second author was supported in part by a National Science Foundation Grant and the California Institute of Technology Laboratory for Experimental Economics and Political Science.     

Dynamic inefficiency in an overlapping generations economy with production

Reichlin [Equilibrium cycles in an overlapping generations economy with production, J. Econ. Theory 40 (1986) 89-102] has shown in an OLG model with productive capital that whenever the steady state is locally indeterminate and undergoes a Hopf bifurcation, it is Pareto-optimal. While these results were established under the assumption of Leontief technology, the author has partially extended them to show that the Hopf bifurcation is robust with respect to the introduction of capital-labor substitution. In this note, we prove that the Pareto-optimality of the steady state does not extend to technologies with capital-labor substitution. When the steady state is a sink or undergoes a Hopf bifurcation, it is characterized by over-accumulation with respect to the Golden Rule—the interest rate is negative—hence not Pareto-optimal. Most importantly, it follows that stabilization policies targeting the steady state leave room for welfare losses associated with productive inefficiency, apart from the very special case of Leontief technology.     

Equilibrium cycles in an overlapping generations economy with production

Perfect foresight equilibrium trajectories of an overlapping generations model with production may include stable or unstable invariant closed curves. These orbits are detected using the Hopf bifurcation theorem, where the parameter of bifurcation is purely technological. The paper also proves that there is a stabilization policy that completely eliminates the cycle. Finally, using a C.E.S. production function, it is shown that the range of values of the elasticity of substitution between capital and labor for which cycles may exist is bounded above.     

Price dynamics in overlapping generations environments

Summary This work examines the existence, uniqueness and computation of competitive equilibria in a class of overlapping generations environments. This set of environments represents a broad generalization of the overlapping generations model considered by Aliprantis and Plott [1]. Two types of results are presented in this paper. First, some general characteristics of perfect foresight competitive equilibrium price paths are developed for economies with finite or countably infinite time horizons and agents with finite lifetimes. The results establish the conditions leading to locally monotonic and locally stable equilibrium prices given arbitrarily many exogenous parameter shifts. Second, these results are strengthened when consideration is focused on a single parametric shift in a finite economy. Existence of a unique equilibrium price path is established. A simple set of rules are given to facilitate computation of this price path for any given shift.The authors wish to express their thanks to Donald Brown, Diego Moreno, Charles Plott, Vernon Smith, and Mark Walker for their comments and suggestions regarding this research.     

Stationary Markov equilibria for overlapping generations

Summary.  At a stationary Markov equilibrium of a Markovian economy of overlapping generations, prices at a date-event are determined by the realization of the shock, the distribution of wealth and, with production, the stock of capital. Stationary Markov equilibria may not exist; this is the case with intra-generational heterogeneity and multiple commodities or long life spans. Generalized Markov equilibria exist if prices are allowed to vary also with the realization of the shock, prices and the allocation of consumption and production at the predecessor date-event. (Stationary) Markov -equilibria always exist; as allocations and prices converge to equilibrium prices and allocations that, however, need not be stationary.Received: 2 March 2004, Revised: 2 April 2004, JEL Classification Numbers:   D50, D52, D60, D80, D90.Correspondence to: Felix KublerWe thank participants in seminars in Athens and Lund, at Penn, at IMPA and at Stanford, the 2002 CEME (NBER) General Equilibrium Conference and the 2002 SED meetings, and especially Martin Hellwig, George Mailath and an anonymous referee for very helpful comments.     

Tax smoothing with immigration in an overlapping generations economy

Immigration policy in an overlapping generations economy is politically determined in response to government spending shocks, where the government finances its spending with proportional income taxes and is subject to a balanced budget. The young cohort is always the majority and dictates policy. The equilibrium Markovian strategy allows immigrants when the spending shock is above some threshold and this implies a particular form of tax smoothing.     

Efficiency in overlapping generations economies with longevity choices and fair annuities

When individuals can influence their life-expectancies and save in annuities, suboptimal savings result from the lack of incentives to choose the optimal longevity, even when annuity returns can be made contingent to longevity-related choices. Specifically, the golden rule steady state maximizing the representative agent utility cannot be attained as a competitive equilibrium under laissez-faire, even with actuarially fair annuities contingent to longevity-enhancing choices. In order to decentralize through markets the golden rule, longevity-enhancing expenditures need to be taxed if the steady state old-age consumption exceeds the annuitized capital return, and subsidized otherwise—the government budget being balanced through lump-sum transfers or taxes. Interestingly, with positive population growth the expected net contribution is negative when longevity-enhancing expenditures are taxed, and positive when subsidized.     

Optimal growth and cycles in overlapping generations models

Summary This paper investigates the dynamical properties of optimal paths in one-sector overlapping generations models without assuming that the utility function of the representative agent is separable. When the utility function is separable, the optimal growth paths monotonically converges toward the modified golden rule steady state. In the non-separable case, we show that the optimal growth path may be oscillating and optimal two-period cycles may exist. Applying these results to the model with altruism, we show that the condition of operative bequest is fully compatible with endogeneous fluctuations provided that the discount factor is close enough to one. All our results are illustrated using Cobb-Douglas utility and production functions.We thank C. Blackorby, J. Blot, P. Cartigny and one anonymous referee for helpful comments and suggestions which generally improved the exposition of the paper. We would also like to thank the participants of the Population and demography session of the European Economic Association 10th Annual Congress (Prague, The Czech Republic, September 1–4, 1995).     

Efficiency and prices in economies of overlapping generations

In a general economy of overlapping generations, I introduce a notion of uniform inefficiency, corresponding to the occurrence of a Pareto improvement with a small uniform destruction of resources [G. Debreu, The coefficient of resource utilization, Econometrica 19 (1951) 273-292]. I provide a necessary and sufficient condition for uniform inefficiency in terms of prices at a competitive equilibrium: an allocation is uniformly inefficient if and only if the relative price of the aggregate endowment in a given period into the aggregate endowment up to that period does not vanish over periods of trade, a sort of Modified Cass Criterion [D. Cass, On capital overaccumulation in the aggregative neoclassical model of economic growth: a complete characterization, J. Econ. Theory 4 (1972) 200-223]. Minimal assumptions on fundamentals are needed for such a complete characterization. Furthermore, proofs reduce to simple and short direct arguments. Finally, I verify that uniform inefficiency is preserved under perturbations, a property that might fail for the canonical notion of inefficiency. Remarkably, an allocation is uniformly inefficient if and only if a non-vanishing redistribution, like a social security mechanism, is welfare improving.     

Habit formation and indeterminacy in overlapping generations models

I introduce habit formation into an otherwise standard overlapping generations economy with pure exchange populated by three-period-lived agents. Habits are modeled in such a way that current consumption increases the marginal utility of future consumption. With logarithmic utility functions, I demonstrate that habit formation gives rise to stable monetary steady states in economies with hump-shaped endowment profiles and reasonably high discount factors. Intuitively, habits imply adjacent complementarity in consumption, which in turn explains why income effects are sufficiently strong in spite of the logarithmic utility. The three-period horizon further strengthens the income effect.     

Monetary equilibrium in an overlapping generations model with productive capital

Summary We study perfect foresight competitive equilibrium in an overlapping generations model with productive capital and a fixed nominal stock of money. We obtain almost-complete characterizations of (a) the existence of a monetary equilibrium from an arbitrary initial capital stock, and (b) the existence of anefficient monetary equilibrium from an arbitrary initial capital stock. When the initial capital stock is no larger than the golden rule stock, the necessary and sufficient condition for both (a) and (b) is the dynamic inefficiency (in the sense of Malinvaud) of the autarkic (or nonmonetary) equilibrium from the same initial stock. However, this condition, though necessary, isnot sufficient for the existence of a monetary equilibrium when the initial stock exceeds the golden rule stock (and still more conditions are needed for anefficient monetary equilibrium to exist). We provide characterizations for these cases, and as corollaries obtain examples in which (a) the nonmonetary equilibrium is inefficient but no monetary equilibrium exists, and (b) monetary equilibria exist but no efficient monetary equilibrium does.We are grateful to a co-editor and an anonymous referee for comments that greatly improved the exposition in the paper.     

Fixed price equilibria in an overlapping generations model with investment

We study fixed price temporary equilibria (with rationing) and sequences of temporary equilibria in a three commodities (goods, labor, bonds) overlapping generations model with endogenous investment. Young consumers, living two periods, work, consume, and buy bonds for financing next period's consumption. New firms, existing for two periods, make a production plan for the next period, taking into account expected rationing, assumed similar to present rationing. The plan determines the amount of goods to buy as capital, financed by bonds. Old firms produce, using labor and the previously bought capital. Different regimes exist and expectations can be self-fulfilling and self-destroying.We are grateful to the referees for helpful comments.