Research Discussion Paper – RDP 9206 Loan Rate Stickiness: Theory and Evidence


Financial deregulation in the 1980s saw the lifting of regulations on interest rates charged by banks. In general, lending rates now respond more quickly to changes in banks' cost of funds than they did in the regulated period. However, lending rates still do not always move one for one with changes in banks' marginal cost of raising funds. This paper canvasses four theoretical explanations, other than collusive behaviour, for loan rate stickiness. These theories are based on equilibrium credit rationing, switching costs, implicit risk sharing and consumer irrationality.

Using regression analysis, we also examine the degree of stickiness of Australian interest rates on secured and unsecured personal loans, credit cards, small and large business overdrafts, and housing loans. We find significant differences in the degree of interest rate stickiness among the different rates, even after allowing for lags in adjustment. The rate on credit cards is found to be the most sticky, followed by personal loan rates, the housing loan rate and the small business overdraft rate. The large business overdraft rate is found to adjust one for one with banks' marginal cost of funds. We briefly examine the behaviour of selected U.S., U.K. and Canadian interest rates. The general order and magnitude of interest rate stickiness is similar to that found for Australia. Although it is not possible to empirically discriminate between the different theories of loan rate stickiness, we interpret the results as providing strong evidence for the switching cost explanation. In addition, implicit risk sharing probably plays an important role in the stickiness of the housing loan rate.

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