Researchers have widely studied CEO tenure because of its importance in predicting FP. CEOs who stay in office for a long time are perceived as experienced in managing stakeholder relationships, which in turn contributes to the firm's economic growth [7–9].

Liu and Jiang [10] show that CEO tenure significantly negatively impacts highly valued firms. The authors explain that CEOs consolidate their power during long tenures rather than focus on investing in innovation and firm development. In particular, the negative effect of CEO tenure is more pronounced in the case of highly valued companies. However, long tenure can lead to the consolidation of managerial power and compromise the board's independence. As a result, this can hinder the board's oversight and thus affect FP [11], [12]. Furthermore, Hambrick and Fukutomi's [13] leader life-cycle model showed that the firm's marginal returns decrease with CEO tenure, which is also confirmed by Chin et al. [14] and Henderson et al. [15]. There is a significant relationship between CEO tenure and company performance.

The CEO can be considered the highest executive power in companies, who has various responsibilities, the most important of which is to develop and implement business strategies, make multiple management decisions, manage the organization's resources and costs, and communicate effectively with the board of directors and other executive bodies in the company [16].

Stable managers can increase cash flows in the firm and improve FP by identifying efficient and profitable intellectual investment opportunities. Stable managers have a greater ability to invest more cheaply in intellectual assets, which can enhance the firm's profitability. According to stewardship theory, the concentration of power gives managers more discretion and can reduce conflicts between shareholders and managers. As a result, this structure maximizes overall benefits by encouraging CEOs to work to achieve the organization's goals [17]. However, this can be a double-edged sword if managers abuse ultimate control for their benefit [18]. Shen et al. [19] and Jeremias and Gani [20] found that CEO duality is detrimental to FP and investment in R&D. Richter and Dalton [21] also suggested that separation of the two powerful positions is more beneficial for better FP.

There is a significant relationship between CEO duality and FP.

CEO ownership refers to the percentage of a company's shares held by the CEO. When the CEO owns part of the company, they have a greater incentive to increase their profitability because their success directly affects the value of their wealth. This ownership relationship aligns the CEO's interests with those of shareholders. Theoretically, managerial ownership solves the agency problem [22]. In both theoretical and practical contexts, CEO ownership is recognized as an important power source [23].

Kaur and Singh [8] argue that when a CEO owns a significant percentage of a company's shares, they can influence the decisions of other managers, thereby creating an opportunity to demonstrate their importance to board members. In addition, significant ownership allows CEOs to control various aspects of the firm, such as determining board members' salaries, regulating dismissals and appointments when necessary, and dominating the organization. Adams et al. [24] and Al-Sila et al. [25] found a positive effect of managerial ownership on firm profitability.

Jeremias and Gani [20] explain that managerial ownership encourages CEOs to engage in activities that maximize the firm's value, as they benefit from the profits of these activities. Similarly, examining corporate leadership's impact on European banks' performance, Onali et al. [23] show that managerial ownership determines bank performance. Conversely, negative effects of CEO ownership on the firm (Abuse of power and bureaucracy) have also been identified [7].

CEO ownership is significantly related to company performance.

The statistical sample of this study includes selected companies listed in the Tehran Stock Exchange (TSE) with the following conditions and within the period from 2013 to 2023 (11 years):

I. The selected samples were listed on the TSE before 2013.

II. To improve comparability, their financial period ends in March.

III. The company did not change its activity or financial year during the years under study.

IV. The company's type of activity is manufacturing; therefore, financial institutions, investment institutions, and banks are not included in the sample.

In this way, the number of companies with the above characteristics that could be used as a statistical sample is 120, so the number of observations is 1320 years-companies.

To test the research hypotheses, Model (1) and Ordinary Least Squares (OLS) regression were used:

FP/ROAi,t = β0 + βkCEOi,t + βjControlsi,t + εi,t (1)

Descriptive statistics deal with the status of the data. Table 1 shows the status of the data as follows:

The results in Table 1 show that tangible assets provide 26 percent of assets. On average, these assets generate 14 percent of profits. On average, 32 percent of profits belong to equity. On average, 66 percent of assets are provided by liabilities. CEOs stay at their companies for an average of 3 years. On average, CEOs own about 17 percent of the company's shares. The rest of Table 2 shows the two-valued variables of the research.

This relationship suggests that the longer a CEO stays in office, the better the company's performance (Measured by ROA). This may be due to the CEO's increased experience and knowledge of the company, the industry, and the business environment. A CEO who stays in the role longer will likely be better able to make strategic decisions, provide management stability, and implement effective policies.

The results of the present study contrast those of Liu and Jiang [7], Al-Matari et al. [11], and Nguyen et al. [12]. During long tenures, CEOs may consolidate their power. Long tenure can consolidate managers' power and affect board independence, impairing board oversight and resulting in poorer business performance.

CEO role duality is when an individual simultaneously serves as CEO and board chairman. The positive relationship between duality and ROA suggests that this concentration of power may contribute to faster and more coordinated decision-making at the management level, improving financial performance. However, it should be noted that this outcome depends on the organization's specific circumstances and the environment and, in some cases, may raise concerns about reduced board oversight.

The results show that the effect of CEO role duality (DUAL) on ROA is significantly positive. This result is inconsistent with the studies of Shen et al. [19] and Jeremias and Gani [20] but consistent with Nguyen et al. [12]. However, this result is also reported by Kaur and Singh [8] and Peni [31], who suggest that the concentration of organizational power allows the CEO greater autonomy and a more assertive leadership style, ultimately improving FP. This view is supported by stewardship theory, which encourages organizational structures to help CEOs use their power in the interests of different groups and the firm. As a result, role duality leads to managers' commitment to improving the firm's performance over the long term.

Our findings are consistent with the studies of Jeremias and Gani [20] and inconsistent with Nguyen et al. [12]. This finding suggests that CEOs with high stock ownership may use their power and control to secure their interests at the expense of the interests of shareholders and other key stakeholders [32].

These actions are detrimental to firm growth in the long run [33]. In other words, owning a certain percentage of the company's shares allows CEOs to intervene in individual decisions made by the board of directors and owners. This situation gives CEOs an information asymmetry advantage, as management teams are closer to the company's day-to-day operations and are well aware of the company's problems. In addition, managers can stay in their positions for extended periods because shared ownership makes it difficult to replace them without their consent [34].

The impact of CEO characteristics may vary across industries or economic sectors, but this study did not control for these differences. This study looked at specific CEO characteristics. Other factors, such as the CEO's personality, communication skills, or leadership style, may influence FP and were not examined in this study.

Based on the results of testing the research hypotheses, the following practical and applicable suggestions have been explained:

Develop policies to prevent excessive consolidation of CEO power during long-term tenure, such as setting a maximum tenure limit and periodic performance evaluations. Also, setting a maximum shareholding limit for CEOs to reduce the possibility of conflicts of interest and prevent negative effects of concentration of power can be an effective factor.

Therefore, developing appropriate measures to investigate the transparency of CEO decisions regarding share ownership may impact FP.

It is suggested that future researchers examine the impact of CEO characteristics (Such as experience, education or gender) and organisational culture on FP. The impact of CEO characteristics may also vary across industries.