Liability-Driven Investment (LDI)

The foundational mechanism of LDI that aligns the interest rate sensitivity of assets with liabilities. By equating the Macaulay duration or key rate duration of the bond portfolio to the duration of the liability stream, the portfolio becomes immunized against parallel shifts in the yield curve. This technique minimizes surplus volatility—the fluctuation in the difference between asset and liability values—ensuring that funding ratio changes are driven primarily by spread and curve reshaping risks rather than outright rate moves.

An extension of Mean-Variance Optimization where the objective function maximizes the return on surplus assets (assets minus liabilities) rather than total assets. The optimization penalizes tracking error relative to the liability benchmark. Key inputs include the surplus efficient frontier and the liability-hedging portfolio. This framework allows plan sponsors to explicitly trade off the cost of hedging liabilities against the potential for generating alpha through a return-seeking portfolio.

A deterministic LDI technique constructing a dedicated bond portfolio where coupon payments and principal redemptions are precisely scheduled to coincide with projected liability outflows. Unlike duration matching, this approach eliminates reinvestment risk and provides a self-liquidating asset stream. The strategy typically uses zero-coupon bonds or strips to avoid interim cash flow timing mismatches, making it the most conservative but often most expensive immunization method.

A sub-portfolio explicitly constructed to track the present value of liabilities. The LHP typically consists of long-duration government bonds, inflation-linked securities, and interest rate swaps. The objective is to minimize the volatility of the funding ratio by maintaining a high correlation with the liability discount curve. The residual capital is allocated to a return-seeking portfolio (RSP) targeting growth assets like equities and alternatives, creating a two-bucket implementation of LDI.

The residual risk that remains even after a portfolio is theoretically immunized against interest rate movements. Sources include:

• Convexity mismatch: Liabilities often exhibit negative convexity while assets have positive convexity
• Curve reshaping risk: Non-parallel shifts like steepening or flattening
• Spread risk: Widening of credit spreads on corporate bonds held as hedging assets
• Basis risk: Imperfect correlation between the hedging instruments and the liability discount curve Effective LDI requires continuous rebalancing to maintain immunization as durations drift.

A dynamic LDI framework that systematically increases the hedge ratio as a pension plan's funded status improves. The strategy defines pre-set triggers—such as achieving a 90% or 100% funding ratio—that automatically shift capital from return-seeking assets into the liability-hedging portfolio. This equity-to-fixed-income transition locks in gains and reduces surplus volatility as the plan approaches full funding, embodying a ratchet mechanism that prevents re-gambling of improved funded status.