This thesis investigates whether investors can earn abnormal returns by mimicking legally reported insider trading in the Swedish stock market. While prior research has shown that insiders often possess valuable information about their firms, less is known about whether outsiders without access to non-public information can benefit by following insider trades. Our study focuses on three sectors: Financial Services, Consumer Goods and Services, and Healthcare and Pharmaceuticals. We apply an event study methodology to insider transactions reported between 2021 and 2024, analyzing stock price reactions across various time windows. We examine both purchase and sale transactions, considering differences in insider position, firm size, and sector. Our findings show that abnormal returns do occur following insider trades, particularly in specific sectors and under certain conditions. For instance, outsider imitation strategies were more effective in the consumer goods and mid-cap healthcare sectors. We also found that purchase transactions tend to generate more consistent positive reactions than sales, though there are exceptions. The results suggest that, despite public disclosure, markets may not immediately absorb insider trading information, especially in contexts with higher information asymmetry. These insights contribute to the ongoing debate about market efficiency and highlight areas where outsiders may still find opportunities in publicly available data.