This paper evaluates the performance of the top 50 companies listed on the Tehran Stock Exchange from 2006 to 2010. A non-probability sampling method was used to select companies with positive liquidity, high turnover, and significant market impact. Using post-modern portfolio theory, the study applied EROV, Sortino, and M³ ratios to assess performance. Statistical analysis using ANOVA and the post-hoc Tukey test revealed significant differences in company performance. However, the results indicated that these companies did not outperform the market. Therefore, the researchers recommend incorporating additional financial and economic factors when selecting the top 50 companies.