credit default swap
https://ru.m.wikipedia.org/wiki/%D0%9A%D1%80%D0%B5%D0%B4%D0%B8%D1%82%D0%BD%D1%8B%D0%B9_%D0%B4%D0%B5%D1%84%D0%BE%D0%BB%D1%82%D0%BD%D1%8B%D0%B9_%D1%81%D0%B2%D0%BE%D0%BF