This thesis aims at contributing to the growing number of studies on banking productivity, by attempting to introduce the interest rate spread as one of the driving forces behind productivity changes and alterations of the intermediary role of banks. The analysis is based on observations form the banking sectors of Germany and Sweden. As there is no clear concensus on the proper way of measuring banking output, and the choice of method varies considerably form study to study, this paper adopts the intermediation approach which is one of the three most offen recurring methods applied in research papers. The results include some interesting revelations such as the low significance of a change in labour and capital to the growth in banking output (challenging traditional theory), and that Swedish banks on average were moving away from the traditional intermediary role between 1979 and 1996 while German banks kept lending business at their centre of attention.