One of the most important innovations in bond financing and in mortgage lending has been the rapid adoption of variable-rate instruments in recent years. Notes and bonds bearing an interest rate between one and two percentage points above the prime rate are becoming common in corporate financing. Similarly, variable-rate mortgages (VRM's) with the interest rate tied to the deposit rate of S&L's or linked to the changing yields on competing investments have spread beyond Florida and California to many states. The Federal Home Loan Bank Board has recently endorsed the variable-rate concept and the Federal Home Loan Mortgage Corporation is preparing guidelines for secondary market operations in VRM's. Portfolio managers are thus taking note of the possibility of acquiring long-term instruments providing some of the resiliency of yields and a measure of real value protection characteristic of short-term issues.

Researchers and political analysts concerned with the inter-regional flow of mortgage funds have often pointed to the existence of yield differentials as prima facie evidence of misallocation of capital and national resources. Limited information and myopic lending horizons, with market imperfections reinforced by state laws and institutional segmentation, have been postulated. They are regarded as responsible for costly “frictions” in the export of capitalto the fast-growing, generally low-income, states, particularly those of the South. Both federal and state legislative action, intensified private arbitrage, and better secondary market facilities and instruments are then urged to improve inter-regional financial mediation to reduce or eliminate the yield differentials.