An Empirical Of Medical Safety Events On A-Share Values In The Stock Market

Since 2002,China's food and medicine fields have had far-reaching events: like plasticizers,lean meat,capsule chromium,exceeding standards and vaccine events.Food and medical safety has always been a global issue that is universally valued by all countries in the world.These incidents have seriously threatened and harmed the health of consumers,and also highlighted the greediness of unscrupulous manufacturers and the lack of safety supervision.of government.From the perspective of investment in the securities market,these events have arisen huge oscillation in stock prices,disrupted the order of the market,and have shocked the relevant enterprises and industries in the A-share market,changed the investor's confidence.This paper used DID method to explore the impact on the stock returns of the pharmaceutical industry due to the ChangShengShengWu "Vaccine fraud" incident which happened on July 15,2018.I analyse the problem from the two perspective of industry and individual company.Through the market adjustment model,we obtain the abnormal returns and explore the impact of vaccine events on the fluctuations of the A-share pharmaceutical industry and its concept stocks returns.I use DID method to detailedly analyze the abnormal returns and the spillover effects of the vaccine industry.It provides the reference for investors' investment decisions and government policies,and inspires the sense of responsibility for medical safety and mutual supervision.The study found that the capital market has a negative reaction to the vaccine incident,and the capital market punishes the enterprises involved in the drug safety responsibility incident.At the same time,the cumulative excess returns of the stocks of the bio-vacuum sector companies have significantly decreased,showing as the “contagion effect”.