Stable Value funds

I have a stable value fund that is comprised of wrapped GIC's.  (Guaranteed investment contract that are underwritten by insurance.)   The fund guarantees a 4.3 % annual return.  If the funds investments fall short, the insurance will cover the difference.  If the fund does better, the insurance company takes the excess.  This scheme sounds like a credit default swap or some other notional instrument.  This is sold as "safe" but I wonder about the insurance companies ability to make good on the deal in a credit crunch.  Are they not also heavily exposed?   (The only reason I am in this fund is because we don't have a cash account option in our 401K.)