The results of the estimation of the fixed effects model indicate that there are significant relation- ships between ROA and market share, labour productivity, firm size, and capital intensity. Other explanatory variables have insignificant effects on ROA. Capital intensity has negative effect, while market share, labour productivity, and firm size have positive effects on ROA. Hypotheses H1 (a), H4 (a), H5 (a), H6 (a) and H7 (a) are supported.