Liability Driven Investing

Section: Liability-Driven Investing (LDI) Estimated study time: 45 minutes Content: Liability-Driven Investing (LDI) is an investment approach where the design of the asset portfolio is explicitly shaped by the structure of the investor's liabilities. Rather than maximizing absolute returns or Sharpe ratio, LDI seeks to match the risk characteristics of assets to liabilities, thereby minimizing surplus volatility — the fluctuation in the difference between asset value and liability value. LDI is most commonly applied to defined benefit (DB) pension funds, insurance companies, and any entity with a predetermined stream of future cash obligations. The core concept in LDI is duration matching. Since liabilities have a duration (sensitivity to interest rate changes), the asset portfolio should be constructed to match or "immunize" that duration. When interest rates fall, the present value of liabilities increases — but so does the value of a long-duration bond portfolio, leaving surplus approximately unchanged. Immunization is most complete when asset duration equals liability duration and the asset/liability cash flow profiles are closely matched. LDI strategies span a spectrum from "beta" (pure liability matching) to "alpha" (return seeking). A liability-matching portfolio (LMP) typically consists of long-duration investment-grade bonds — including long-maturity Treasuries, strips, and corporate bonds — designed to track liability movements closely. A return-seeking portfolio (RSP) contains higher-return assets (equities, alternatives) intended to improve funding status over time. The optimal split between LMP and RSP depends on the fund's current funded status: underfunded plans may tilt toward RSP to close the gap; well-funded or overfunded plans tilt toward LMP to lock in funding. The liability benchmark is critical to LDI implementation. Liabilities are typically discounted using a high-quality corporate bond yield curve (for US private…