1.1. The concept of matching assets and liabilities has for many years been recognized as a crucial aspect of our professional work. Its importance is emphasized in the Institute's guidance notes entitled “Actuaries and Long-Term Insurance Business” and in many papers published in the Journal.

1.2. A particular form of matching, namely immunization, was developed by F. M. Redington in his paper “Review of the Principles of Life-Office Valuations” (J.I.A. 78, 286). Immunization signifies the investment of assets in such a way that the existing business is immune to a change in the rate of interest. One of the consequences of immunization is that the mean term of the asset-maturity dates is appreciably longer than the mean term of the value of the asset-proceeds and of the liability-outgo; and, at other than low rates of interest, a perpetuity can be too short to immunize a long-term contractual liability.