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An Anatomy of the “S&P Game”: The Effects of Changing the Rules
Author(s) -
BENEISH MESSOD D.,
WHALEY ROBERT E.
Publication year - 1996
Publication title -
the journal of finance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 18.151
H-Index - 299
eISSN - 1540-6261
pISSN - 0022-1082
DOI - 10.1111/j.1540-6261.1996.tb05231.x
Subject(s) - stock (firearms) , index (typography) , economics , period (music) , monetary economics , zoology , history , biology , philosophy , computer science , aesthetics , archaeology , world wide web
This study analyzes the effects of changes in S&P 500 index composition from January 1986 through June 1994, a period during which Standard and Poor's began its practice of preannouncing changes five days beforehand. The new announcement practice has given rise to the “S&P game” and has altered the way stock prices react. We find that prices increase abnormally from the close on the announcement day to the close on the effective day. The overall increase is greater than under the old announcement policy although part of the increase reverses after the stock is included in the index.