PV (protection leg) - PV (premium leg ) = upfront payment
“Protection leg is the contigeent payment that credit protection seller may have to make to the credit protection buyer; and the premium leg is the series of payment the credit proteion buyer promises tomake to the credit protection seller.” p.357
anyone can explain why
when PV (protection leg) more than PV (premium leg), the CDS buyer will have to pay the seller?