The growing competition in the business world today, resulting in company managers must have a strategy so that the company can run better and can maintain the success of the company. A successful firm is one that can meet its corporate objectives. A company's purpose to make shareholders prosperous by maximizing company value. Therefore, the higher the company value shows that more investors are eager to put money into the business (Buhaenah & Pradana, 2022). Firm value is the investor's view of a company's success rate in managing its resources, as evidenced by its stock price. A high stock price raises the company's value and boosts market confidence in its performance now and in the future (Bahriah et al., 2022).

Among those nations with a sizable Muslim populace is Indonesia. This makes many Indonesians want to apply Islamic sharia principles in Indonesia. Therefore, there are many Islamic capital markets in Indonesia (Rasyid et al., 2022). The Jakarta Islamic Index 70 is a group of Indonesia's Islamic stock indices that estimates the average share price index for stocks that meet Islamic standards. or principles. With the existence of the Jakarta Islamic Index 70, it is hoped that it can become a benchmark for investors in choosing sharia-based stocks and to develop the Islamic capital market. JII 70 is an alternative for Indonesian investors who are generally Muslim people who want to invest their funds in sharia without fear of being mixed with ribawi funds. In addition, the benefits obtained by investors from investment returns are based on the principle of profit sharing (Hamzah Muchtar et al., 2021). The development of the Jakarta Islamic Index 70 at the end of June 2021, closed at 193.59 or decreased by 12.09% compared to the end of 2020. The capitalization of the JII70 as of the end of June 2021 closed at the level of IDR2,295.59 trillion or experienced a decrease of 9.17% compared to the end of 2020. When compared to March 24, 2020, the JII70 index has experienced an increase of 46.97% and an increase in market capitalization value of 45.23% (Keuangan, 2021). The development of investor interest in investing in Islamic stocks is certainly due to investors increasingly believing in Islamic stocks from companies that have good corporate value (Sari et al., 2023). Therefore, the higher the company value, the more investors are interested in investing in the company (Buhaenah & Pradana, 2022). Firm value is the investor's perception of the company's success rate in managing the company's resources which can be seen from its stock price. A high stock price makes the company value also high, and increases market confidence in the company's performance not only now but also in the future (Bahriah et al., 2022).

There are several factors that affect firm value, such as capital structure, investment decision, and firm size. An optimal capital structure is something that can increase the market value of the company's outstanding s hares. Optimal capital structure means that it has an influence on firm value where the capital structure can change in order to obtain optimal firm value (Telaumbanua et al., 2021).

Capital structure is one of the most important considerations for investors in making investments, it is related to investment risk and income that will be received by investors (Bahriah et al., 2022). According to (Telaumbanua et al., 2021); (Bahriah et al., 2022): (Rohaeni et al., 2020); (Syamsudin et al., 2020): (Rasyid et al., 2022) capital structure has a positive and significant effect on firm value. In contrast to research (Ramadhani et al., 2021); (Afifah & Prajawati, 2022); (Buhaenah & Pradana, 2022) capital structure has a negative effect on firm value. Whereas research by (Permadani et al., 2021) capital structure does not affect firm value.

The second factor that is considered to affect firm value is investment decisions. The right investment decision will produce optimal performance. The more companies make the right investment, the more optimal the company's performance will be. Choosing a profitable investment is not easy and requires several considerations because investment decisions that only focus on financial information alone do not guarantee that the investment decisions made are correct. Investment is a commitment to a number of funds or other resources made at this time with the aim of obtaining a number of benefits in the future (Yulli, 2019).

According to (Mulyani & Oktaviani, 2022); (Silaturahmi & Novitasari, 2022); (Larasati & Arrozi, 2022); (Syamsudin et al., 2020); (Yulli, 2019) firm value is significantly and favorably impacted by investment decisions. Meanwhile, studies indicate. (Sari & Yudiantoro, 2023), (Panjaitan et al., 2023) investment decisions have a detrimental impact on firm value. For the research of (Rahmawati & Wijaya, 2022), (Hariyanur et al., 2022) investment decisions doesn’t have effect on firm value.

The firm's size, as determined by its total assets, can be employed for operational purposes. Large total assets make it easier for companies to solve funding problems for company needs. From the management perspective, the simplicity with which it controls the company will raise the company's worth. (Rohaeni et al., 2020).

According to (Firda & Efriadi, 2020); (Rohaeni et al., 2020); (Hidayat & Khotimah, 2022); (Dina & Wahyuningtyas, 2022) firm size has a positive and significant effect on firm value. Furthermore, according to (Bahriah et al., 2022) firm size has a negative effect on firm value. Whereas according to (Rasyid et al., 2022); (Khotimah et al., 2020) firm size has no effect on firm value.

Profitability in this study is a moderating variable where the variable is thought to be able to strengthen or weaken a variable that affects the dependent variable. Profitability is one of the factors that also affects the value of the company. ROA measures the company's ability to generate profits using the total assets the company has after adjusting for the costs of funding these assets. Because generally an investor sees how a company's ability to generate profits to make it more convincing to invest in the company. Profitability is projected using ROA (Return on Asset) which is a measure of the effectiveness of management in managing its investment (Sari & Yudiantoro, 2023). The addition of the firm size variable to the research object-the Jakarta Islamic Index 70-and the research period 2019-2022 is novelty of the research.

Research Variable

The debt-to-equity ratio (DER) serves as the study's independent variable. This measurement refers to (Syamsudin et al., 2020) research with the following formula:

Investment Decisions

The second independent variable in this study is investment decisions as measured by the price earnings ratio (PER). This measurement refers to (Syamsudin et al., 2020) research with the following formula:

Firm Size

Another independent variable is firm size that measured by the natural logarithm of total asset (Ln Total Asset). This measurement refers to (Bahriah et al., 2022) research with the following formula:

Ln= Ln Total Asset

Firm Value

The dependent variable in this study is firm value as proxied by price book value (PBV). This measurement refers to (Ramadhani et al., 2021) research with the following formula:

Profitability

This study's moderating variable is profitability, as assessed by return on assets (ROA). This measurement refers to (Dina & Wahyuningtyas, 2022) research with the following formula:

The Influence of Capital Structure on Firm Value

The first hypothesis to be tested is whether capital structure affects firm value in JII70. Table 6 displays the results of the research hypothesis testing. With a coefficient value of 0.8177363, Hypothesis 1 testing shows a positive relationship between capital structure and firm value. This demonstrates that profitable organizations tend to incur more debt. The more successful a company is, the more likely it will incur debt. The corporation can utilize the extra interest to pay lower taxes on increasing corporate profits. Additional debt only modestly raises the chance of bankruptcy for a corporation that is financially solid. In other words, a sensible firm will expand debt if it may boost the company's earnings. (Syamsudin et al., 2020).

The trade-off principle can be applied to the capital structure since the company will incur debt up to a certain level where tax savings outweigh the cost of financial issues. Trade-off theory has been considered in determining the optimal capital structure by incorporating the optimal capital structure into several factors including taxes, agency costs, and the cost of financial difficulties, but there is still the issue of maintaining assumptions and symmetric information as rewards and benefits in the use of debt. (Siswanti & Ngumar, 2019). This research is in line with research (Telaumbanua et al., 2021); (Bahriah et al., 2022); (Syamsudin et al., 2020), (Rasyid et al., 2022); (Silvia & Toni, 2020) shows that the capital structure has a positive effect on firm value.

The Influence of Investment Decisions on Firm Value

The second hypothesis to be tested is whether investment decisions affect firm value in JII70. Table 6 displays the results of testing the research hypothesis. With a coefficient value of -0.0005529, Hypothesis 2 testing shows that there is no relationship between investment decisions and firm value, especially companies with the JII70 index that go public on the Indonesia Stock Exchange. The deviating research results obtained show that the composition of the company's asset growth according to stakeholders, particularly investors owned by the company, does not jeopardize the company's condition, so it is assumed that it will have no effect on changes in the company's value, particularly as measured by the price earning ratio. This condition suggests that rising investment decisions made by shareholders or investors outside of the company do not always have an impact on its value. Given the existence of a number of external risk variables, such as exchange rate variations, inflation, and interest rate fluctuations. Each of these variables cannot be handled, and the magnitude of the change in value is uncertain, yet they make a significant influence (Jesilia & Purwaningsih, 2020). The research conducted is in line with research by (Jesilia & Purwaningsih, 2020); (Rahmawati & Wijaya, 2022); (Tanggo & Taqwa, 2020) which states that investment decisions have no effect on firm value.

The Influence of Firm Size on Firm Value

The third hypothesis to be tested is whether investment decisions affect firm value in JII70. Table 6 displays the results of testing the research hypothesis. With a coefficient value of 0.7718966, hypothesis 3 testing shows no influence between firm size on firm value.The number of assets owned by the company has no bearing on the issue of funding needs used in the company's operating activities, according to the conclusion that, for companies listed in the JII70 index 2019–2022, the size of the company (size) has no significant effect on the value of the company (PBV). (Rohaeni et al., 2020). Large company size does not necessarily guarantee high company value, because large companies may not necessarily dare to make new investments related to expansion, before the obligations (debt) have been paid off, on the other hand, in investing capital investors do not only look at the size of the company but investors still consider many other factors that become investors' considerations in channeling their funds. Such as growth and increase in company profits (Khotimah et al., 2020). This study supports the findings of (Khotimah et al., 2020); (Rohaeni et al., 2020) study, that firm size has no significant effect on the value of the company.

Profitability is able to moderate capital structure on firm value

The fourth hypothesis to be tested is whether Profitability is able to moderate capital structure on firm value in JII70. Table 6 displays the results of the research hypothesis testing. With a coefficient value of 4.001555, Hypothesis 4 testing shows that Profitability is able to moderate capital structure on firm value. With the increase in debt, the company obtains funds to develop business operations so as to increase company profits. If the use of debt provides benefits that are greater than the sacrifices incurred by the company, such as the benefits of tax deductions greater than the interest expense incurred by debt, the use of debt can increase the company's net profit (Buhaenah & Pradana, 2022). The higher the DER value, the lower the risk borne by the company in paying debt so that it will increase investor confidence (Permadani et al., 2021). This study supports the findings of (Buhaenah & Pradana, 2022); (Permadani et al., 2021); (Ramadhani et al., 2021); (Syamsudin et al., 2020) that Profitability is able to moderate capital structure on firm value.

Profitability is able to moderate investment decisions on firm value

The fifth hypothesis to be tested is whether Profitability is able to moderate investment decisions on firm value in JII70. Table 6 displays the results of the research hypothesis testing. With a coefficient value of 2.661939, Hypothesis 5 testing shows that Profitability is able to moderate investment decisions on firm value. Investors see this company's increased profits as a sign of strength in this instance. Naturally, investors are drawn to businesses with promising futures in the hopes that the stock price of the company will rise. The company's value is positively impacted by rising stock prices as well. Investors are interested in entrusting their capital to the company due to its high profitability (Mulyani & Oktaviani, 2022). In order to attract investors, a company with a high PER value typically offers strong growth prospects and is a good investment. Investors will value the shares more than what is shown on the balance sheet of the company due to the strong demand for shares. As a result, a higher stock price suggests that the company is worth more. Having said that, a company's return on investment (or profit) increases with the amount of money invested in it. This attracts more investors and raises the firm's value (Syamsudin et al., 2020). This research is in line with (Silaturahmi & Novitasari, 2022); (Rahmawati & Wijaya, 2022); (Syamsudin et al., 2020); (Mulyani & Oktaviani, 2022) shows Profitability is able to moderate investment decisions on firm value.

Profitability is able to moderate company size on firm value

The last hypothesis to be tested is whether Profitability is able to moderate firm size on firm value in JII70. Table 6 displays the results of the research hypothesis testing. With a coefficient value of 2.283844, Hypothesis 6 testing shows that Profitability is unable to moderate firm size on firm value. From the calculation results and decision-making criteria, it can be concluded that partially profitability (ROA) is not able to moderate the effect of company size (size) significantly on firm value (PBV) in JII70 indexed companies for the 2019-2022 period. This means that the company is unable to earn profits from the assets owned by the company so that it weakens the capital funding policy which then becomes unable to optimize the company's value (Rohaeni et al., 2020). This research is in line with (Rohaeni et al., 2020); (Rasyid et al., 2022); (Khotimah et al., 2020) Profitability is unable to moderate firm size on firm value.

According to the findings of the preceding study, the results of this study indicate that capital structure affects firm value, investment decisions and firm size have no effect on firm value, profitability is able to moderate the effect of capital structure and investment decisions on firm value, while profitability is unable to moderate firm size on firm value.

The company should provide more complete and clear information in order to reduce asymmetry from several sources regarding the company's financial condition. Companies that have good prospects should use internal and external funds as well as possible, especially for financial managers in calculating the effective use of financing or funding from external sources and paying attention to the capital structure and profitability that may be in accordance with the needs of the company's operational activities. The company will make considerations in the use of external funds such as debt because if the company has high debt, investors can provide high debt and obtain high profits which affect the company's value.

It is expected that investors if they want to make an investment should consider the company's financial condition regarding the capital structure of the company's value by choosing a company from a good level of profitability in order to produce high company value.