In this video, we dive into the concept of market efficiency, specifically focusing on the different forms of market efficiency: weak, semi-strong, and strong. We explore how investors can use public and private information to generate abnormal returns, depending on the efficiency of the market. Using a practical framework, we assess various statements and their implications for stock prices and investor behavior. The video covers critical aspects such as the role of historical data, public information, and insider trading in determining market efficiency. For instance, under a weak form market, investors can potentially use public and private data to achieve abnormal returns, while under a semi-strong form, only private information would give investors an edge. The video also explains why certain statements about capital markets and investor returns are incorrect based on the efficiency assumption. Through these real-world examples, we highlight how to evaluate market conditions and make informed investment decisions. Understanding the efficiency of markets is crucial for both students and professionals to navigate the complexities of the stock market and develop strategies for better risk management and return generation.