학술논문

Estimating the Dynamics of Mutual Fund Alphas and Betas.
Document Type
Article
Source
Review of Financial Studies. Jan2008, Vol. 21 Issue 1, p233-264. 32p. 9 Charts, 2 Graphs.
Subject
*Mathematical statistics
*Mutual funds
*Mathematical models of investments
*Mathematical models of finance
*Economic models
*Estimation theory
*Economic forecasting
Prediction theory
Kalman filtering
Least squares
Language
ISSN
0893-9454
Abstract
This article develops a Kalman filter model to track dynamic mutual fund factor loadings. It then uses the estimates to analyze whether managers with market-timing ability can be identified ex ante. The primary findings are as follows: (i) Ordinary least squares (OLS) timing models produce false positives (nonzero aiphas) at too high a rate with either daily or monthly data. In contrast, the Kalman filter model produces them at approximately the correct rate with monthly data; (ii) In monthly data, though the OLS models fail to detect any timing among fund managers, the Kalman filter does; (iii) The alpha and beta forecasts from the Kalman model are more accurate than those from the OLS timing models; (iv) The Kalman filter model tracks most fund alphas and betas better than OLS models that employ macroeconomic variables in addition to fund returns. [ABSTRACT FROM AUTHOR]