View source for Definition:Modified duration

📉 '''Modified duration''' is a measure of the sensitivity of a [[Definition:Fixed-income security | fixed-income instrument's]] price to changes in [[Definition:Interest rate | interest rates]], and it plays a central role in how [[Definition:Insurance carrier | insurance companies]] manage the [[Definition:Investment portfolio | investment portfolios]] that back their [[Definition:Reserve | policyholder reserves]] and [[Definition:Surplus | surplus]]. Expressed in years, it estimates the percentage change in a bond's market value for a one-percentage-point shift in yield — a bond with a modified duration of 5, for example, would lose roughly 5 percent of its value if rates rose by 100 basis points.

⚙️ Insurance investment teams use modified duration as the primary tool for [[Definition:Asset-liability management (ALM) | asset-liability matching]]. The goal is to align the duration of the asset portfolio with the duration of expected [[Definition:Claim | claims]] payouts and other liabilities so that interest rate movements affect both sides of the balance sheet in roughly equal measure. A [[Definition:Property and casualty insurance | property and casualty]] insurer with short-tail liabilities might target a portfolio modified duration of two to three years, whereas a [[Definition:Life insurance | life insurer]] holding long-dated [[Definition:Annuity | annuity]] obligations could extend duration well beyond ten years. When mismatches arise, insurers may use [[Definition:Derivative | derivatives]] — interest rate swaps or Treasury futures — to fine-tune the hedge.

🏦 Regulators and [[Definition:Rating agency | rating agencies]] scrutinize duration positioning as part of their broader assessment of an insurer's financial resilience. A significant duration gap — where asset duration is materially shorter or longer than liability duration — can amplify the impact of rate volatility on [[Definition:Statutory capital | statutory capital]] and [[Definition:Risk-based capital (RBC) | risk-based capital]] ratios. In the rising-rate environment experienced in the early 2020s, insurers with overly long asset durations suffered mark-to-market losses that strained balance sheets, underscoring why disciplined duration management is considered a foundational competency in insurance [[Definition:Enterprise risk management (ERM) | enterprise risk management]].

'''Related concepts:'''
{{Div col|colwidth=20em}}
* [[Definition:Asset-liability management (ALM)]]
* [[Definition:Duration]]
* [[Definition:Interest rate risk]]
* [[Definition:Investment portfolio]]
* [[Definition:Risk-based capital (RBC)]]
* [[Definition:Fixed-income security]]
{{Div col end}}