You are assessing the dynamics of the stock price of a firm around its earnings announcement.

a. If the firm announces better earnings than expected, and the market is semi-strong efficient, what do you expect to observe to its market price right after the announcement? What about during the entire month after the announcement?

b. A friend of yours tells you that she found positive and statistically significant abnormal returns around such event when using the CAPM. She claims that she found positive alphas also when using the Fama-French three-factor model, the Fama-French five-factor model, and even when adding the momentum factor to all the five factors of the latter model. She thus concludes that "for sure the market is not semi-strong efficient given these alphas". Is she correct? Explain why you agree or disagree with her.