Marketplace Tech is exploring investment technology as part of the Divided Decade project on the financial crisis of 2008. This is the second half of host Molly Wood’s conversation with Brad Katsuyama, whose IEX stock exchange aims to address some of the negative impacts of high-frequency trading by slowing down the system — by a whole 350 millionths of a second. This speed bump caused what Katsuyama calls “one of the biggest controversies” in the stock market’s recent history as IEX sought approval. (09/19/18)