LDI Hedge Ratios and Leveraged Gilt Strategies

A defined-benefit pension fund owes retirees a stream of payments decades into the future. Value that promise today and — because it's discounted at a market interest rate — it behaves exactly like a very long-dated bond: when rates fall, the present value of the liability rises, sometimes dramatically, since a small change in the discount rate compounds over thirty or forty years of payments. A pension scheme that holds mostly equities and only a modest allocation to bonds is, without realizing it, running a large bet that rates will rise. Liability-driven investing (LDI) is the discipline of turning that accidental bet off — holding a portfolio of government bonds and derivatives specifically sized so that when the liability's value moves, the assets move with it.

Why leverage enters the picture

The obvious way to hedge is to hold enough government bonds — gilts, in the UK — to match the liability pound for pound. But a fully funded pension scheme's actual pool of assets is usually smaller than the present value of its liabilities on a low-discount-rate basis, and the scheme also wants some of its money invested in equities and other growth assets to help close any funding gap over time. Holding 100% of assets in low-yielding gilts to match a liability that's worth more than the assets is arithmetically impossible without leverage.

The solution is to use leveraged LDI: hold a smaller pool of gilts (or gilt repo positions and interest-rate swaps) but scale up their interest-rate sensitivity using borrowing, so that a relatively small slice of the portfolio delivers the interest-rate hedge that would otherwise require the whole fund. This frees up the rest of the assets to be invested in equities, credit, and other return-seeking assets, while the leveraged gilt sleeve does the job of tracking the liability's rate sensitivity.

Hedge ratio	What it means	Typical scheme posture
0%	No interest-rate hedge; assets and liabilities move independently	Rare — usually only very early-stage or heavily underfunded schemes
50-70%	Partial hedge; some residual rate risk retained	Common for schemes still building toward full funding
90-100%+	Assets closely track liability moves; funding ratio is stable through rate swings	Common for well-funded, mature schemes near buyout

The leverage itself is achieved mainly through repo — borrowing cash against gilts already held as collateral, and using that cash to buy more gilts — or through interest-rate swaps and gilt total-return swaps that deliver rate exposure without owning the full notional in bonds. Both routes require posting collateral, and both routes work fine as long as gilt yields move smoothly. The mechanism has a weak point precisely there.

A worked scenario: collateral calls when yields move fast

A pension scheme holds $100 million of leveraged gilt exposure structured through repo, giving interest-rate sensitivity equivalent to roughly $400 million of unleveraged gilts against a liability of similar size. Under normal conditions this works exactly as intended: gilt yields drift a little each week, the scheme's collateral position shifts a little each week, and the fund manager tops up or releases collateral in the ordinary course of business, funded from a modest cash buffer set aside for that purpose.

Now suppose gilt yields jump by 100 basis points in a matter of days — an extreme move by historical standards, but not unprecedented. The leveraged gilt position, with four times the rate sensitivity of an unleveraged holding, loses value fast, and the repo counterparties issue collateral calls demanding more cash or gilts be posted, right away, to keep the borrowing in place. If the scheme's cash buffer isn't large enough to meet the call, it has to sell assets — ideally liquid ones held for exactly this purpose, but under time pressure, sometimes the gilts backing the hedge itself. Selling gilts into a market where yields are already spiking pushes yields higher still, which triggers the next round of collateral calls across every scheme running a similar strategy at the same time.

The lesson schemes and regulators drew afterward was less about the hedge ratio itself and more about the liquidity buffer sitting behind it: a leveraged position needs enough readily available collateral, sized to a genuinely extreme move, not just a typical one, or the hedge can end up amplifying the very risk it was built to remove.