A practice whereby an intermediary enters into one side of the swap transaction, such as a fixed rate payer (or a floating rate payer) to a client who wishes to be a floating rate payer (or a fixed rate payer). Then the intermediary waits for a matching counterparty and offloads the swap thereto. In other words, swap warehousing involves holding a portfolio of swaps usually by a swap dealer without seeking to offset each swap with an identical mirror swap. In this sense, the swap dealer becomes a counterparty to every swap held in its portfolio. The dealer earns, for its services as a dealer, a pay-receive spread (bid-ask spread) which is equal to the difference between the swap coupon the dealer pays and swap coupon the dealer receives.

Swap warehousing is also known as swap positioning or booking a swap.