Peterffy is talking out of his ass, they had more than 5 days. CME's current specifications for order entry/market data has been in place for years now. Whoever was writing their software on their backend failed to read the documentation.
While I don't doubt that what you say is true, systems which, by spec, should be able to handle a given situation, that then years after they were written finally are called upon to handle that situation, fail more often than not.
The CEO also said they would pay $100million to clean up, which is not chump change, even for them I bet.
I'm not saying they were blameless, but I think most systems which have never had a given variable go negative, that years after they were written finally have that variable go negative, will have problems.
Nat gas prices went negative pretty famously (in the biz) around 2010 or so. I give everyone a pass based on what you said until then. After that no free passes. IB screwed up.
CME requires certification before you can deploy a connector to them.
If they really cared or if this was as obvious as everyone here is claiming it is, negative price support would be part of their certification suite. It is not.
The CEO also said they would pay $100million to clean up, which is not chump change, even for them I bet.
I'm not saying they were blameless, but I think most systems which have never had a given variable go negative, that years after they were written finally have that variable go negative, will have problems.