The Significance of the Market Portfolio
The market portfolio (world portfolio) is in one sense a least important portfolio to provide to investors; there is always a better portfolio for social planners to make available to them. In a J-agent one-period stochastic endowment economy, where preferences are quadratic, the market portfolio is never spanned by the optimal markets a social planner would create. With identical preferences, the market portfolio is orthogonal to all J - 1 portfolios which achieve a first best solution. These conclusions rely on the assumption that the social planner has perfect information about agents' utilities. We also show that as the contract designer's information about agents' utilities becomes more imperfect, the optimal contracts approach contracts that weight individual endowments in proportion to elements of eigenvectors of the variance matrix of endowments. If there is a substantial market component to endowments than a social planner, for reasons of robustness and simplicity, may conclude that creating a contract to allow trading the market portfolio would be a significant innovation.
|Date of creation:||Jun 1997|
|Date of revision:|
|Publication status:||Published in The Review of Financial Studies (Summer 2000), 13(2): 301-329|
|Contact details of provider:|| Postal: |
Phone: (203) 432-3702
Fax: (203) 432-6167
Web page: http://cowles.econ.yale.edu/
More information through EDIRC
|Order Information:|| Postal: Cowles Foundation, Yale University, Box 208281, New Haven, CT 06520-8281 USA|
References listed on IDEAS
Please report citation or reference errors to , or , if you are the registered author of the cited work, log in to your RePEc Author Service profile, click on "citations" and make appropriate adjustments.:
- Gyutaeg Oh, 1996. "Some Results in the CAPM with Nontraded Endowments," Management Science, INFORMS, vol. 42(2), pages 286-293, February.
- Duffie Darrell & Rahi Rohit, 1995. "Financial Market Innovation and Security Design: An Introduction," Journal of Economic Theory, Elsevier, vol. 65(1), pages 1-42, February.
- Geanakoplos, John, 1990. "An introduction to general equilibrium with incomplete asset markets," Journal of Mathematical Economics, Elsevier, vol. 19(1-2), pages 1-38.
- Cass, David & Chichilnisky, Graciela & Wu, Ho-Mou, 1996. "Individual Risk and Mutual Insurance," Econometrica, Econometric Society, vol. 64(2), pages 333-41, March.
- Demange Gabrielle & Laroque Guy, 1995. "Optimality of Incomplete Markets," Journal of Economic Theory, Elsevier, vol. 65(1), pages 218-232, February.
- Magill, Michael & Shafer, Wayne, 1991. "Incomplete markets," Handbook of Mathematical Economics, in: W. Hildenbrand & H. Sonnenschein (ed.), Handbook of Mathematical Economics, edition 1, volume 4, chapter 30, pages 1523-1614 Elsevier.
When requesting a correction, please mention this item's handle: RePEc:cwl:cwldpp:1154. See general information about how to correct material in RePEc.
For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (Glena Ames)
If references are entirely missing, you can add them using this form.