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A swaption is a type of option that gives the holder the time-limited right to enter an interest rate swap or credit default swap (CDS) at a pre-set rate at expiry in exchange for a premium payment.
For interest rates, an option to enter a pay-fixed, receive-floating swap is known as a payer, while a receiver would deliver the opposite position. For credit, an option to purchase CDS protection is known as a payer, and the opposite is a receiver.
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