Abstract
Portfolio turnpikes state that as the investment horizon increases, optimal portfolios for generic utilities converge to those of isoelastic utilities. This paper proves three kinds of turnpikes. In a general semimartingale setting, the abstract turnpike states that optimal final payoffs and portfolios converge under their myopic probabilities. In diffusion models with several assets and a single state variable, the classic turnpike demonstrates that optimal portfolios converge under the physical probability. In the same setting, the explicit turnpike identifies the limit of finite-horizon optimal portfolios as a long-run myopic portfolio defined in terms of the solution of an ergodic HJB equation.
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Notes
A subset A of Ω is N-negligible if there exists a sequence (B n ) n≥0 of subsets of Ω such that for all n≥0, we have \(B_{n} \in\mathcal{F}_{n}\) and \(\mathbb {P}[B_{n}]=0\), and A⊂⋃ n≥0 B n . This notion is introduced in [2, Definition 1.3.23] and [43]. Such a completion of \(\mathcal {F}_{0}\) ensures, for all T≥0, that the space \((\varOmega, \mathcal {F}_{T}, (\mathcal{F}_{t})_{0\leq t\leq T}, \mathbb {P})\) satisfies the usual conditions. Hence all references below on finite-horizon problems with completed filtration can be used in this paper.
For any ϵ>0, there exists M ϵ such that U′(x)≤(1+ϵ)x p−1 for x≥M ϵ . Integrating the previous inequality on (M ϵ ,x) yields \(U(x) \leq(1+\epsilon)(x^{p}-M^{p}_{\varepsilon })/p + U(M_{\varepsilon })\), when x≥M ϵ and 0<p<1, from which the claim follows. The proof for the case p=0 is similar.
The notation \(\widetilde{\mathbb {Q}}\)-lim T→∞ is short for the limit in probability under \(\widetilde{\mathbb {Q}}\).
Since R 0=0 by assumption, \(\mathbb {P}^{\xi}\) with ξ=(0,y) is denoted as \(\mathbb {P}^{y}\). The same convention applies to other probabilities introduced later.
In the model (2.7) and (2.8), u 0,T depends on the initial value of the state variable Y 0=y. Hence u T is a function of y. Since Proposition 2.5 reduces the problem to the comparison of the optimal isoelastic finite-horizon portfolio with its long-run limit, the superscript 0 will be omitted in this section.
Any y 0∈E suffices. This y 0 is chosen to align m with \(\hat{m}\).
If a logarithmic investor is present (γ i =1 for some i), a constant is added to U(x), and the stated equivalence remains valid.
References
Benninga, S., Mayshar, J.: Heterogeneity and option pricing. Rev. Deriv. Res. 4, 7–27 (2000)
Bichteler, K.: Stochastic Integration with Jumps. Encyclopedia of Mathematics and Its Applications, vol. 89. Cambridge University Press, Cambridge (2002)
Bielecki, T.R., Pliska, S.R.: Risk sensitive asset management with transaction costs. Finance Stoch. 4, 1–33 (2000)
Bielecki, T.R., Hernandez-Hernandez, D., Pliska, S.R.: Risk sensitive asset management with constrained trading strategies. In: Yong, J. (ed.) Recent Developments in Mathematical Finance, Shanghai, 2001, pp. 127–138. World Scientific, River Edge (2002)
Cheridito, P., Summer, C.: Utility maximization under increasing risk aversion in one-period models. Finance Stoch. 10, 147–158 (2006)
Cheridito, P., Filipović, D., Yor, M.: Equivalent and absolutely continuous measure changes for jump-diffusion processes. Ann. Appl. Probab. 15, 1713–1732 (2005)
Cox, J.C., Huang, C.: A continuous-time portfolio turnpike theorem. J. Econ. Dyn. Control 16, 491–507 (1992)
Cvitanić, J., Malamud, S.: Price impact and portfolio impact. J. Financ. Econ. 100, 201–225 (2011)
Delbaen, F., Schachermayer, W.: A general version of the fundamental theorem of asset pricing. Math. Ann. 300, 215–250 (1994)
Delbaen, F., Schachermayer, W.: The fundamental theorem of asset pricing for unbounded stochastic processes. Math. Ann. 312, 463–520 (1998)
Detemple, J., Rindisbacher, M.: Dynamic asset allocation: portfolio decomposition formula and applications. Rev. Financ. Stud. 23, 25–100 (2010)
Dybvig, P.H., Rogers, L.C.G., Back, K.: Portfolio turnpikes. Rev. Financ. Stud. 12, 165–195 (1999)
Evans, L.C.: Partial Differential Equations. Graduate Studies in Mathematics, vol. 19. American Mathematical Society, Providence (1998)
Feller, W.: Two singular diffusion problems. Ann. Math. 54, 173–182 (1951)
Fleming, W.H., McEneaney, W.M.: Risk-sensitive control on an infinite time horizon. SIAM J. Control Optim. 33, 1881–1915 (1995)
Fleming, W.H., Sheu, S.J.: Risk-sensitive control and an optimal investment model. Math. Finance 10, 197–213 (2000)
Fleming, W.H., Sheu, S.J.: Risk-sensitive control and an optimal investment model. II. Ann. Appl. Probab. 12, 730–767 (2002)
Friedman, A.: Partial Differential Equations of Parabolic Type. Prentice-Hall, Englewood Cliffs (1964)
Friedman, A.: Stochastic Differential Equations and Applications. Vol. 1. Probability and Mathematical Statistics, vol. 28. Academic Press/Harcourt Brace Jovanovich, New York (1975)
Goll, T., Kallsen, J.: A complete explicit solution to the log-optimal portfolio problem. Ann. Appl. Probab. 13, 774–799 (2003)
Guasoni, P., Robertson, S.: Portfolios and risk premia for the long run. Ann. Appl. Probab. 22, 239–284 (2012)
Guasoni, P., Robertson, S.: Static fund separation of long-term investments (2013). Math. Financ. Available at http://onlinelibrary.wiley.com/doi/10.1111/mafi.12017/abstract
Hakansson, N.H.: Convergence to isoelastic utility and policy in multiperiod portfolio choice. J. Financ. Econ. 1, 201–224 (1974)
Heath, D., Schweizer, M.: Martingales versus PDEs in finance: an equivalence result with examples. J. Appl. Probab. 37, 947–957 (2000)
Huang, C.-F., Zariphopoulou, T.: Turnpike behavior of long-term investments. Finance Stoch. 3, 15–34 (1999)
Huberman, G., Ross, S.: Portfolio turnpike theorems, risk aversion, and regularly varying utility functions. Econometrica 51, 1345–1361 (1983)
Jacod, J., Shiryaev, A.N.: Limit Theorems for Stochastic Processes, 2nd edn. Grundlehren der Mathematischen Wissenschaften, vol. 288. Springer, Berlin (2003). [Fundamental Principles of Mathematical Sciences]
Jin, X.: Consumption and portfolio turnpike theorems in a continuous-time finance model. J. Econ. Dyn. Control 22, 1001–1026 (1998)
Kabanov, Y., Kramkov, D.: Asymptotic arbitrage in large financial markets. Finance Stoch. 2, 143–172 (1998)
Kaise, H., Sheu, S.J.: On the structure of solutions of ergodic type Bellman equation related to risk-sensitive control. Ann. Probab. 34, 284–320 (2006)
Kallsen, J.: Optimal portfolios for exponential Lévy processes. Math. Methods Oper. Res. 51, 357–374 (2000)
Karatzas, I., Kardaras, C.: The numéraire portfolio in semimartingale financial models. Finance Stoch. 11, 447–493 (2007)
Karatzas, I., Žitković, G.: Optimal consumption from investment and random endowment in incomplete semimartingale markets. Ann. Probab. 31, 1821–1858 (2003)
Kardaras, C.: The continuous behavior of the numéraire portfolio under small changes in information structure, probabilistic views and investment constraints. Stoch. Process. Appl. 120, 331–347 (2010)
Kramkov, D., Sîrbu, M.: On the two-times differentiability of the value functions in the problem of optimal investment in incomplete markets. Ann. Appl. Probab. 16, 1352–1384 (2006)
Kramkov, D., Sîrbu, M.: Sensitivity analysis of utility-based prices and risk-tolerance wealth processes. Ann. Appl. Probab. 16, 2140–2194 (2006)
Kramkov, D., Sîrbu, M.: Asymptotic analysis of utility-based hedging strategies for small number of contingent claims. Stoch. Process. Appl. 117, 1606–1620 (2007)
Larsen, K., Žitković, G.: Stability of utility-maximization in incomplete markets. Stoch. Process. Appl. 117, 1642–1662 (2007)
Leland, H.: On turnpike portfolios. In: Szego, G., Shell, K. (eds.) Mathematical Methods in Investment and Finance, p. 24. North-Holland, Amsterdam (1972)
Mossin, J.: Optimal multiperiod portfolio policies. J. Bus. 41, 215–229 (1968)
Nagai, H., Peng, S.: Risk-sensitive optimal investment problems with partial information on infinite time horizon. In: Yong, J. (ed.) Recent Developments in Mathematical Finance, Shanghai, 2001, pp. 85–98. World Scientific, River Edge (2002)
Nagai, H., Peng, S.: Risk-sensitive dynamic portfolio optimization with partial information on infinite time horizon. Ann. Appl. Probab. 12, 173–195 (2002)
Najnudel, J., Nikeghbali, A.: A new kind of augmentation of filtrations. ESAIM Probab. Stat. 15, 39–57 (2011)
Pinchover, Y.: Large time behavior of the heat kernel and the behavior of the Green function near criticality for nonsymmetric elliptic operators. J. Funct. Anal. 104, 54–70 (1992)
Pinchover, Y.: Large time behavior of the heat kernel. J. Funct. Anal. 206, 191–209 (2004)
Pinsky, R.G.: Positive Harmonic Functions and Diffusion. Cambridge Studies in Advanced Mathematics, vol. 45. Cambridge University Press, Cambridge (1995)
Rogers, L.C.G., Williams, D.: Diffusions, Markov Processes, and Martingales. Vol. 2. Itô Calculus, Cambridge Mathematical Library. Cambridge University Press, Cambridge (2000). Reprint of the second (1994) edition
Ross, S.: Portfolio turnpike theorems for constant policies. J. Financ. Econ. 1, 171–198 (1974)
Zariphopoulou, T.: A solution approach to valuation with unhedgeable risks. Finance Stoch. 5, 61–82 (2001)
Acknowledgements
We are grateful to the Associate Editor and two anonymous referees for carefully reading this paper and providing valuable suggestions, which greatly assisted us in improving this paper.
Paolo Guasoni is partially supported by the ERC (278295), NSF (DMS-0807994, DMS-1109047), SFI (07/MI/008, 07/SK/M1189, 08/SRC/FMC1389), and FP7 (RG-248896). Constantinos Kardaras is partially supported by the NSF DMS-0908461. Hao Xing is partially supported by an LSE STICERD grant.
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Guasoni, P., Kardaras, C., Robertson, S. et al. Abstract, classic, and explicit turnpikes. Finance Stoch 18, 75–114 (2014). https://doi.org/10.1007/s00780-013-0216-5
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DOI: https://doi.org/10.1007/s00780-013-0216-5