Event Studies:How Tests Are Structured Event Studies are one type of test of the semi-strong form of market efficiency. This form of the EMH implies that prices should reflect all publicly available information. To test this,event studies examine prices and returns over time-particularly around the arrival of new information. Test for evidence of under reaction, overreaction,early reaction,delayed reaction around the event. 2222 Event Studies: How Tests Are Structured Event Studies: How Tests Are Structured • Event Studies are one type of test of the semi-strong form of market efficiency. 9 This form of the EMH implies that prices should reflect all publicly available information. • To test this, event studies examine prices and returns over time—particularly around the arrival of new information. • Test for evidence of under reaction, overreaction, early reaction, delayed reaction around the event