The S&P 500 effect: not such good news in the long run
AbstractThis paper analyzes the effect on a company's stock price when it is added to the S&P 500 Index. A simple theoretical model is developed to show how trading effects and changes to fundamentals should affect the price of S&P500 additions upon announcement and in the long run. This model predicts that a company added to the S&P500 should experience an initial price increase followed by a reversal of this price increase owing to the predicted increased stock price volatility of companies post-addition. All of these effects should be growing over time because of the increasing importance of S&P500 indexed mutual funds. We test the predictions of the model using a sample of 303 S&P500 Index additions between 1978 and 1998. We find results generally consistent with the model, particularly in the most recent period when it appears that the post-addition increase in stock price volatility reverses almost all of the initial price increase.
Download InfoIf you experience problems downloading a file, check if you have the proper application to view it first. In case of further problems read the IDEAS help page. Note that these files are not on the IDEAS site. Please be patient as the files may be large.
Bibliographic InfoPaper provided by Board of Governors of the Federal Reserve System (U.S.) in its series Finance and Economics Discussion Series with number 2002-48.
Date of creation: 2002
Date of revision:
This paper has been announced in the following NEP Reports:
- NEP-ALL-2002-12-09 (All new papers)
- NEP-FIN-2002-12-09 (Finance)
- NEP-FMK-2002-12-09 (Financial Markets)
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.:
- Kraus, Alan & Stoll, Hans R, 1972. "Price Impacts of Block Trading on the New York Stock Exchange," Journal of Finance, American Finance Association, vol. 27(3), pages 569-88, June.
- Pagan, Adrian, 1984. "Econometric Issues in the Analysis of Regressions with Generated Regressors," International Economic Review, Department of Economics, University of Pennsylvania and Osaka University Institute of Social and Economic Research Association, vol. 25(1), pages 221-47, February.
- J. Bradford De Long & Andrei Shleifer & Lawrence H. Summers & Robert J. Waldmann, .
"Noise Trader Risk in Financial Markets,"
J. Bradford De Long's Working Papers
_124, University of California at Berkeley, Economics Department.
- Lynch, Anthony W & Mendenhall, Richard R, 1997. "New Evidence on Stock Price Effects Associated with Changes in the S&P 500 Index," The Journal of Business, University of Chicago Press, vol. 70(3), pages 351-83, July.
- Dhillon, Upinder & Johnson, Herb, 1991. "Changes in the Standard and Poor's 500 List," The Journal of Business, University of Chicago Press, vol. 64(1), pages 75-85, January.
For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (Kris Vajs).
If references are entirely missing, you can add them using this form.