Pricing SOFR Futures and Understanding Convexity Adjustments
Summary
The document explains how one-month and three-month SOFR futures are defined and why their theoretical rates differ. The one-month contract reflects average daily SOFR over its delivery month, while the three-month contract reflects compounded daily SOFR over its reference quarter; the quoted futures settlement value is expressed as 100 minus the rate. In normal market use, liquid futures rates are observed directly and help build the short end of interest rate curves.
For contracts without observable market prices or for future exposure simulation, a pricing model can derive a rate from the SOFR curve. The text gives continuous-time risk-neutral expectation expressions for the averaging and compounding conventions. It cautions that model-free derivations omit the convexity effects associated with futures discounting, so practical theoretical pricing requires a specified interest-rate model. No particular model calibration, numerical example, or empirical comparison is supplied.
Key ideas
- One-month SOFR futures reference average daily SOFR over the delivery month.
- Three-month SOFR futures reference compounded daily SOFR over the reference quarter.
- Market quotes generally supply liquid futures rates used to construct short-term interest rate curves.
- Theoretical pricing can use risk-neutral expectations when a contract rate is not directly observable.
- Convexity adjustments require an interest-rate model and are not captured by the model-free expressions.
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Full text
# Theoretical fair value of SOFR 1M and 3M Future contracts?
# Theoretical fair value of SOFR 1M and 3M Future contracts?
The fair value of Eurodollar future contracts is calculated using the no arbitrage pricing and the spot curve for LIBOR. How does one compute the theoretical fair value of 1M and 3M SOFR Future contracts?
## Answer by Daneel Olivaw (score 4, accepted)
https://quant.stackexchange.com/a/59522
(Edit 23.11.2020) [Note that my previous derivations were too hasty and had some issues, I will try to amend when time allows. In any case, note that those results were merely model-free: SOFR Futures have convexity adjustments and in practice you will need to specify a model for the forward rates to actually calculate them. Feel free to unmark as "answered".]
First off, let us recall how the CME group defines SOFR Future rates $F$:
- 1M SOFR future rate: "average daily SOFR interest during contract Delivery Month".
- 3M SOFR future rate: "compounded daily SOFR interest during contract Reference Quarter".
The settlement value of the Future is then equal to: $100-F$.
As @JanStuller explains, Futures are normally liquid instruments. They are used as building blocks for constructing interest rate curves, especially over the short-end that is maturities equal to or less than 1 year. Therefore, the Future rate is given by the market, rather than derived from a pricing model.
That being said, there might be circumstances under which you want to price a Future not observable in the market. For example, you might want to price a long-dated Future which is yet not being actively traded in the market. Another example is when computing valuation adjustments such as CVA: these require simulating Future rates at future times; you then normally simulate the interest rate curve and use a pricing model to obtain a simulated Future rate from your curve.
It is possible to derive a model-free expression for the SOFR Future rate. However bear in mind that, due to the neglect of discounting in Futures, there are convexity adjustments in the rate's calculation. To compute those adjustments you actually need a model for the rates.
## Answer by Frido (score 2)
https://quant.stackexchange.com/a/83673
A bit late to the party, but since I don't see formulas in the previous answers (which doesn't mean they're wrong!) I'll add those:
Let $r(t)$ be the SOFR rate.
Under a continuous time approximation you can write at time $t$ for the 1 month future, $$ \mathrm{1MFut} = \frac1\delta \mathbb E_t^\mathbb Q \left[ \int_T^{T+\delta} r(u) du \right], $$ and for the 3 month future, $$ \mathrm{3MFut} = \frac1\delta \mathbb E_t^\mathbb Q \left[ e^{\int_T^{T+\delta} r(u) du} \right], $$ where $\mathbb Q$ is the usual risk-neutral measure and $t \leq T+\delta$.
Lastly, one needs to choose a particular model to calculate the theoretical futures prices above.Shown in full with attribution under the source's licence. Licence: CC BY-SA 4.0 (Stack Exchange)
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.