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Why Do Demand Curves for Stocks Slope Down?


  • Antti Petajisto


Representative agent models are inconsistent with existing empirical evidence for steep demand curves for individual stocks. This paper resolves the puzzle by proposing that stock prices are instead set by two separate classes of investors. While the market portfolio is still priced by individual investors based on their collective risk aversion, those individual investors also delegate part of their wealth to active money managers who use that capital to price stocks in the cross-section. In equilibrium the fee charged by active managers has to equal the before-fee alpha they earn; this endogenously determines the amount of active capital and the slopes of demand curves. A calibration of the model reveals that demand curves can indeed be steep enough to match the magnitude of many empirical findings, including the price effects for stocks added to (or deleted from) the S&P 500 index.

Suggested Citation

  • Antti Petajisto, 2004. "Why Do Demand Curves for Stocks Slope Down?," Yale School of Management Working Papers amz2458, Yale School of Management, revised 01 Sep 2008.
  • Handle: RePEc:ysm:somwrk:amz2458

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    References listed on IDEAS

    1. Barberis, Nicholas & Thaler, Richard, 2003. "A survey of behavioral finance," Handbook of the Economics of Finance,in: G.M. Constantinides & M. Harris & R. M. Stulz (ed.), Handbook of the Economics of Finance, edition 1, volume 1, chapter 18, pages 1053-1128 Elsevier.
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    4. Berk, Jonathan B, 1995. "A Critique of Size-Related Anomalies," Review of Financial Studies, Society for Financial Studies, vol. 8(2), pages 275-286.
    5. Jonathan B. Berk & Richard C. Green, 2004. "Mutual Fund Flows and Performance in Rational Markets," Journal of Political Economy, University of Chicago Press, vol. 112(6), pages 1269-1295, December.
    6. Allen, Franklin & Gale, Douglas, 1994. "Limited Market Participation and Volatility of Asset Prices," American Economic Review, American Economic Association, vol. 84(4), pages 933-955, September.
    7. Franklin Allen, 2001. "Presidential Address: Do Financial Institutions Matter?," Journal of Finance, American Finance Association, vol. 56(4), pages 1165-1175, August.
    8. Franklin Allen, 2001. "Do Financial Institutions Matter?," Center for Financial Institutions Working Papers 01-04, Wharton School Center for Financial Institutions, University of Pennsylvania.
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