R&D investments under financing constraints.

We analyse the effect of credit supply constraints on R&D conditional on the financial strength of firms and heterogeneity in the restrictions in the supply of external financing. The financial strength of firms and access to external financing are identified by an exogenously calculated rating index. Restrictions in the supply of external financing are determined by the specific time period (crisis vs. non-crisis) and the balance sheet strength of the firm's main bank in terms of bank capital. Our results support the theoretical prediction that financing constraints negatively affect R&D. We find that firms with a lower financial strength reduce R&D to a stronger extent in times of stress on financial markets and when the firm faces restrictions in external financing. Additionally, the effect does not persist over time. [ABSTRACT FROM AUTHOR]