1 Characteristics of capital structure and Shareholder’s value: An application on the FTSE All-Share Index-London market Abdulhadi Ramadan Al-Isra University, Jordan Mahmoud Nassar Applied Science Private University, Jordan Muhannad Atmeh German Jordanian University, Jordan Mazen Alomary Al-Zarqa University, Jordan Abstract The relationship between debt level and a firm’s performance is a focal point for most of the capital structure theories especially agency theory, signalling and asymmetric information theory, and trade-off theory. The issue of capital structure is concerned with the optimum mix of debt and equity in the financing structure. This optimal capital structure concludes in minimum weighted average cost of capital, and consequently maximizes the firm’s performance in terms of shareholders’ value. Reasonable theoretical as well as empirical researches try to define the determinants of capital structure, but research investigating the important role of these determinants of capital structure on financial performance is limited. This research attempts to investigate whether the link between the determinants of capital structure and a firm’s performance exists in the UK context. Assuming that the debt level is determined by a number of factors which called in this research the “determinants of capital structure”; and the debt level influence the firm’s financial performance; then it is reasonable to expect that determinants of capital structure would also influence the firm’s financial performance. Consequently; this research aims to answer these questions empirically:  What is the relationship between debt level and a firm’s financial performance?  What is the relationship between the determinants of capital structure and a firm’s financial performance? METHODOLOGY: Most of the data used in this study will be collected from secondary sources including the annual reports for nonfinancial companies in the UK. Sample of this research will cover FTSE All-Share Index which considered the most recent constituent list. It is the aggregation of the FTSE 100, FTSE 250 and FTSE SmallCap Indices. FTSE provides details of all companies that are currently constituents of their FTSE All-World index. FTSE World stock-level data, including constituent lists, provide daily, monthly, and yearly data for Europe, Americas, and Asia Pacific. The final sample is 425 companies after excluding eight firms due to the unavailability of its data in the database. Moreover, this study uses the Stata to test the study relationships. Stata can be applied for panel data studies and it gives the related tests which are not available in other software packages. This research tends to cover a relatively long period from 1992 to 2006. It deemed necessary to select long period in order to draw sound statistical estimations for relationships assigned to be tested in this research. Since it is not expected that each