When does a fixed rate swap cost more than a floating rate

07 September 2026

A fixed rate swap costs more than a floating rate swap when market conditions, swap size, or counterparty risk make the fixed-rate provider demand a premium to lock in a rate for you. The difference appears as a wider spread between the fixed quote and the floating index rate.

Why fixed rates carry a premium

Fixed rate quotes are not magic numbers. They are calculated from the current floating rate plus an adjustment for risk. The provider who offers you a fixed rate takes on a liability: they guarantee that rate for the entire swap, no matter what the market does next. If the floating rate moves against them, they absorb the loss. That risk has a price.

The premium shows up in two ways:

The rate itself is higher. A fixed rate quote will always be slightly above the current floating rate, because it must cover the provider's expected cost of hedging their exposure. They need to offset your fixed leg with floating positions elsewhere, and that hedge costs money.

The spread widens as the swap gets larger. This is where the hub page's subject - "When the swap size moves the market rate" - becomes relevant. A small fixed rate swap might cost only a few basis points more than floating. But as the amount grows, the provider cannot hedge without affecting the market. Placing a large hedge moves the floating rate against them. They pass that cost back to you as a wider spread. At a certain size, the fixed quote can be substantially worse than the floating rate you would get by simply accepting a variable quote.

When the cost difference becomes obvious

Several conditions make the fixed rate notably more expensive:

High volatility. In a calm market, the premium is small. When prices swing wildly, the provider's hedge becomes riskier and more expensive to maintain. They raise the fixed rate to compensate.

Thin liquidity for the asset or pair. If the asset trades infrequently, the provider cannot easily hedge without moving the market. The fixed quote will carry a large premium over floating.

Long swap duration. A fixed rate for a 24-hour swap costs less than a fixed rate for a 7-day swap. The longer the commitment, the more uncertainty the provider must price in.

Large swap size relative to market depth. This is the core mechanism described on the hub page. When your swap amount exceeds a noticeable fraction of daily trading volume, the fixed rate quote will be significantly worse than the floating rate. The provider must either hedge in a way that moves the market, or accept unhedged risk. Both outcomes make the fixed rate more expensive.

When floating might cost you more

Floating rates are not always cheaper. They are cheaper at the moment you see the quote. But the floating rate can change during the swap. If the market moves against you before the swap settles, you could end up paying more than the fixed rate would have been. The fixed rate is insurance against that movement. You pay the premium upfront to avoid the risk.

The decision is not about which rate is lower right now. It is about whether you want to pay a known cost to eliminate uncertainty, or accept variable cost to avoid the premium. The larger the swap, the more expensive that insurance becomes.

The hub page explains the mechanism

For swaps large enough that the rate itself changes because of your order, the fixed rate premium can become dramatic. The page "When the swap size moves the market rate" describes exactly how that happens. It is the next logical read if you are deciding whether to accept a fixed quote or ride the floating rate.

Back to exchange fees