Corporate diversification involves expanding activities and investments in different economic areas. In this regard, there are two theories. According to the first theory, increasing the level of diversity in an organization increases accrual measurement errors and reduces their quality, ultimately leading to a decrease in the stability and quality of profits. However, according to the second theory, diversified companies have multiple sources of income due to the expansion of activities and therefore have higher and more stable profits. Therefore, the present study was conducted to examine these two theories on a targeted sample of 160 selected companies on the Tehran Stock Exchange from 2015 to 2019. Given the different and possible behavior of companies in order to establish these two theories, companies should first be clustered based on profit stability and the proposed model should be fitted to the data of each cluster. The results of this study showed that in small and medium-sized companies in terms of diversity, the first theory is valid, and in large companies with high diversity, the second theory is valid. That is, by creating diversity and after the period attributed to the first theory has passed, companies can be in the second theory phase and experience more stable financial performance. Also, other results showed that diversification and accruals have a positive and negative effect on the return on assets in each cluster, respectively, and on the other hand, the interaction of these two variables (which determines the results of examining the two theories) has a negative effect in the first cluster and a positive effect in the second cluster.