This thesis investigates the relationship between product market competition and zero leverage behavior within firms, aiming to uncover how these dynamics interact. Additionally, it explores whether firms characterized by higher earnings volatility exhibit a more pronounced positive relationship between product market competition and the likelihood of adopting a zero-leverage strategy. To carry out this investigation, we employed product market competition data (Fluidity) from the Hoberg-Phillips Data Library and financial data from the Compustat (North America) database, spanning from 1989 to 2019. As product market competition intensifies, the probability of firms adopting a zero leverage policy increases. Furthermore, our research illuminates that the positive impact of heightened product market competition on the likelihood of zero leverage policies is accentuated in firms characterized by elevated levels of earnings volatility. This finding corroborates our initial hypothesis, substantiating the notion that increased competition significantly influences a company's earnings volatility. We also strengthened our analysis with insights from existing literature, underscoring how heightened earnings volatility intensifies the propensity to embrace a zero leverage policy. This study contributes insights to the literature, notably as the first to employ the interaction term between product market competition and earnings volatility in exploring these financial dynamics.

The first chapter evaluates the zero-leverage effect on firms' financial constraints. Moreover, using investment- and cash-to-cash-flow sensitivities as financial constraint indicators, the results suggest that unleveraged firms are expected to face lower constraints relative to leveraged firms. Lastly, the results indicate that the zero-leverage effect on firms’ financial constraints is more likely stronger for smaller firms, zero-dividend firms, firms with lower proportions of tangible assets, and growth firms. The second chapter develops a new quantitative measure that reflects the extent to which a firm complies to Shariah relative to the other firms located in a certain region at a certain time. This measure can be customized to be consistent with each investor’s objectives, constraints, and beliefs. We argue that the use of this measure is preferable to the existing use of ratio thresholds for the following two reasons. First, it is more Shariah-appropriate because it provides the Shariah-compliant investor with a clear understanding of the relative compliance status of each firm he wishes to invest in. Second, it can be incorporated into any portfolio optimization model to create a balance between improving Shariah compliance and not compromising investment returns.

This study investigates why some firms have no debt in their capital structure despite the potential benefits of leverage. A logistic regression analysis is used to examine the impact of firm-specific characteristics on a firm’s propensity to have zero leverage. The validity of five theoretical explanations for the zero-leverage phenomenon are examined based on how the theories predict characteristics to affect a firm’s propensity to be unlevered. Analysing a new sample of Swedish firms listed on Nasdaq Stockholm in 2005-2018, I show that on average 14.2% of all firms are unlevered. The regression results suggest that the phenomenon of zero-leverage firms can be explained by a combination of several theories. Some firms seem forced to follow zero-leverage policies due to credit rationing by lenders. Others appear to be deliberately debt-free either because they have low needs of external financing or because they strategically want to avoid debt. The study’s main findings for zero-leverage firms are also robust to firms with very low debt (book leverage less than 5%).