Determinants of Optimal Capital Structure and Speed of Adjustment: Evidence from the U.S. ICT Sector

We employ a dynamic adjustment model (Flannery and Rangan, 2006) to investigate the determinants of capital structure and speed of adjustment (Drobetz and Wanzenried, 2006) in a panel of 85 U.S. ICT firms over the years 1990 to 2013. We estimate the capital structure using a wide range of factors commonly used in the empirical literature (growth and investment opportunities, profitability, firm size, default risk, and industry median capital structure). We expand on this literature to include two additional determinants: asset turnover, an inverse measure of firm agency costs (Morellec, et al., 2012; Ang, Cole, and Lin, 2000), and R&D activity (Aghion, et al., 2004). We find that the speed of adjustment increases with firm size, growth opportunities, and distance from the target capital structure, and decreases with default risk and agency costs. We also find that R&D expenditures and agency costs cause firms to maintain lower levels of debt. We employ four recently developed estimators in dynamic panel-data econometrics: the double-censored fractional estimator (Elsas and Florysiak, 2011), the bias-corrected least-squares dummy-variable estimator (Bruno, 2005), the iterative bootstrap-based bias correction for the fixed-effects estimator (Everaert and Pozzi, 2007), and the fixed-effects quasi-maximum-likelihood estimator (Kripfganz, 2016; Hsiao, et al., 2002). In addition, our panel-data regression results show that in the ICT sector, the leverage ratio exhibits high persistence. Moreover, it positively relates to growth and investment opportunities, firm size, capital investment, and industry median capital structure, and negatively relates to profitability and default risk.