Conversion Factor (Bond Futures)
A conversion factor is a standardizing multiplier assigned by the CME Group to each Treasury security eligible for delivery into a Treasury futures contract, computed as the price at which the deliverable bond would trade to yield 6% — the notional coupon assumed by the futures contract — on the first day of the delivery month.
Treasury futures contracts are designed to represent a standardized notional bond rather than any specific Treasury security. Because the deliverable basket contains bonds with different coupons and maturities, a conversion factor system is used to adjust the invoice price paid by the futures buyer when any specific bond is delivered, allowing securities with varying characteristics to compete on an approximately equal basis for delivery.
The conversion factor for a given bond is calculated as the present value of the bond's remaining cash flows — coupons and principal — discounted at an annualized yield of 6%, divided by the bond's face value, as of the first day of the delivery month. This computation is performed by the CME Group and published before the delivery period. Bonds with coupons above 6% will have conversion factors greater than 1.0, while bonds with coupons below 6% will have conversion factors less than 1.0.
The invoice price paid by the long futures position upon delivery is: Invoice Price = Futures Settlement Price x Conversion Factor + Accrued Interest. The conversion factor thus adjusts the futures settlement price to approximate the fair value of the specific bond being delivered, given the 6% yield assumption.
However, the 6% notional yield assumption is purely a convention that rarely matches actual market yields. This mismatch creates a systematic distortion: at current yield levels well below 6% in most of the post-2008 period, conversion factors have tended to overstate the relative value of high-coupon bonds and understate the relative value of low-coupon bonds, producing a persistent cheapest-to-deliver dynamic rather than a level playing field across the basket.
Conversion factors play a central role in futures pricing and hedging. The hedge ratio for a Treasury futures position — the number of futures contracts needed to hedge a given bond portfolio — depends on the ratio of the portfolio DV01 to the futures DV01, where the futures DV01 is itself derived from the CTD bond DV01 adjusted by the conversion factor. Misapplication of conversion factors in hedge ratio calculations is a common source of hedging error, particularly when the CTD bond switches during the life of the hedge.