People walk past the NASDAQ MarketSite in Times Square after trading was halted on all Nasdaq-listed stocks on August 22, 2013 in New York City. - 

Pull up a chart of the Nasdaq on Thursday and you see something crazy: a flat line for hours. Nasdaq halted all trading because of a technical glitch. Things were fixed just before the market close, but many are still looking for answers.

Chris Low, chief economist at FTN Financial, joins Marketplace's Mark Garrison to discuss why glitches like this are bound to keep happening.

Audio Extra: David Weild, former Nasdaq chairman, discusses Thursday's trading glitch and market complexity.

Follow Mark Garrison at @GarrisonMark