We have multiple layers of firewalls and filtering. Our pricing logic can identify when a bad quote is in the book and discard it, so pricing is not vulnerable to a sweep. We also configure alerting for when normal conditions are no longer occurring, which causes a review by a human to ensure the pricer is behaving as expected. 

There are separate kill switches for pricing and hedging. There are also kill switches per asset class, in case there are only issues with a small subset of instruments