Also, it's pretty sure that it's fixed the software glitch and that won'tprobably won't might not happen again.
The Chicago Board Options Exchange said preparations to extend trading hours led to last week's shutdown of one of the largest U.S. stock-options markets, even though staff were aware of potential problems ahead of time.
The exchange operator said Monday in a note to clients that an internal review left it "fully confident" that it had addressed the software bug, though it would be assessing how it handled the 3½-hour outage last Thursday….
CBOE said the root cause of the outage lay in "preliminary staging work" in preparation for longer trading hours on CBOE's futures and options markets, according to the notice sent by CBOE executives….
The staging work being done at CBOE "exposed and triggered a design flaw in the existing messaging infrastructure configuration," according to the notice. People briefed on the CBOE's investigation said late last week that the problem was seen related to the exchange's software for the handling of complex, multipart options orders. A spokeswoman for CBOE declined further comment Monday.