- What we knew: "Flash Boys" author Michael Lewis would be joining CNBC's Power Lunch.
- What we didn't know: William O'Brien, chief executive of BATS, and Brad Katsuayama, CEO and president of IEX, would get into a heated debate on high-frequency trading.
"Shame on both of you for falsely accusing literally thousands of people and possibly scaring millions of investors in an effort to promote a business model," O'Brien said to Lewis and Katsuayama.
"Do you believe [the markets] are rigged?" O'Brien asked Katsuayama, "because you said it."
"I believe the markets are rigged," he answered, "and I also think you are a part of the rigging."
- From there, cheers and boos were heard on the sidelines at the NYSE, while those on Twitter yelled from homes and offices worldwide.
- Did you miss it? Catch it in all its glory here: