Portfolio Immunization with Contingent Features

A Hybrid Approach

Contingent immunization is a "hybrid" portfolio management strategy that seeks to combine the best of active management and passive immunization. The strategy allows a portfolio manager to actively manage a portfolio with the goal of earning a return that is higher than the available immunization rate. However, it also incorporates a safety net: if the portfolio's performance deteriorates to a pre-determined trigger point, the active management ceases, and the portfolio is immediately immunized to lock in a minimum acceptable return.

This strategy is appealing to clients, such as pension funds, who have a minimum required return that they must meet but who also want the potential for higher returns from active management.

Setting Up the Strategy

The first step in setting up a contingently immunized portfolio is to determine the minimum acceptable return. This is the "floor" return. Based on the current yield curve, the manager can calculate the return that could be locked in today via a standard immunization strategy. This is the "immunization rate." The difference between the initial portfolio value and the present value of the floor return represents the "cushion" or "surplus" that the manager has to work with.

Cushion = Initial Portfolio Value - PV(Floor Liability)

As long as this cushion is positive, the manager is free to pursue active strategies, such as duration bets, sector rotation, or security selection, in an attempt to generate returns above the immunization rate. The value of the portfolio will be monitored continuously. If the portfolio suffers losses from the active strategies such that the cushion shrinks to zero, the trigger point is reached.

The Trigger Point

When the market value of the portfolio has fallen to the point where it is just sufficient to fund the floor liability at the current immunization rate, the active strategy has failed. The manager must immediately take action to immunize the portfolio. This means liquidating the active portfolio and purchasing a portfolio of bonds that matches the duration of the floor liability. By doing so, the manager locks in the floor return and ensures that the client's minimum requirement is met.

For example, a pension fund has $100 million and a required floor return of 4% over a 5-year horizon. The current 5-year immunization rate is 5%. The present value of the $100 million growing at 4% for 5 years is $121.67 million. The present value of this liability at the 5% immunization rate is $95.35 million. The initial cushion is $100M - $95.35M = $4.65 million. The manager can actively manage the $100 million portfolio. If the portfolio's value falls to $95.35 million, the cushion is gone, and the manager must immunize.

Active Management within the Strategy

The size of the cushion dictates the aggressiveness of the active strategy. A larger cushion allows the manager to take on more risk. For example, if the cushion is large, the manager might take a significant duration bet or allocate a larger portion of the portfolio to high-yield bonds. As the cushion shrinks, the manager must become more conservative. The active strategies used are the same as in any other actively managed portfolio, but they are always constrained by the need to protect the floor.

Contingent immunization is an elegant solution to the classic trade-off between risk and return. It provides the discipline of a passive strategy with the opportunity of an active one. It gives the manager the freedom to pursue alpha, while giving the client the assurance that their downside is protected. The key to success is diligent monitoring and the discipline to pull the trigger and immunize if and when the cushion is exhausted.