Firms can use different sources of external knowledge for developing and implementing innovations. Some knowledge is provided deliberately by the source and constitutes intended knowledge spillovers, e.g., knowledge disclosed in publications or patent files. Other sources represent unintended...

Most of the empirical literature on the relationship between firm value and knowledge capital is based on the stock market valuation. We use a credit rating score as an alternative measure. Innovative firms with a reasonable knowledge stock achieve a better rating, whilst too many innovative...