Swap assignments are actions taken by a counterparty to a swap (such as an interest rate swap) to effectively terminate the swap from its side by finding a third party who wants to assume the rights and obligations under the original swap for the remaining time in its tenor.

On the other hand, swap unwinds involve terminating the swap before its maturity in order to monetize the market value of the swap position. The counterparty willing to unwind a swap will enter into an equal but opposite position for the remaining life of the original swap. Unwinds can be done in several ways such as reverse swaps, swap assignment (swap sale), or swap cancellation.

In this sense, assignments are unwinds carried out with a third party. In an assignment, a new party (usually a bank or financial institution) replaces one of the counterparties to the original swap, and will be responsible for the next payment (of the net amount). For example, if bank A has a swap with bank B and wants to assign it to bank C, the result would be a swap between bank B and bank C based on the same terms of the original swap between bank A and bank B. If the original swap is in the money (ITM) for bank A, bank C would be out of the money (OTM) and would pay bank A the net amount. If the swap is out of the money for bank A, then bank A would pay bank C to take over obligations. The net amount paid need never be disclosed to the counterparty to the original swap, i.e., bank B. Payments for assignments are usually adjusted for accrued interest for the current period of the swap. However, in economic terms, there are practically no difference in valuation between the two methods.