Nanex Research

Nanex ~ 13-Sep-2013 ~ CBOE Halts, Stops Retail and Dark Pool Trading

Starting around 10:45:30 on September 13, 2013, quotes abruptly stopped from the CBOE, causing the NBBO to cross in hundreds of stocks. When the NBBO (National Best Bid/Offer) crosses, it shuts down Dark Pool and Retail trading because they rely on a valid NBBO, and a crossed NBBO (when bid price is greater than ask price) is an invalid NBBO. Step through charts showing this phenomenon in 8 stocks.

Nanex Research

Inquiries: pr@nanex.net