Abstract: To some extent we can not find expected market reaction,which should be logically consistent to the financial performance,to the announcement of annual report in some Chinese listed companies.Somebody concludes that it is due to the investors’ignorance of the information of performance.Is this conclusion true?Since nobody knows the SARS event in details until the Chinese government announced the truth on April 20.This provides us with a good opportunity to test whether the market reaction to an announcement with full information is rational.Put SARS as matching event,we argue that the release in advance should play an important role in the explanation on the reaction to annual report.

Key words: event study, announcement, release of information, SARS