Nathaniel Popper is currently the journalist in residence at the Tarbell Fellowship. He is the author of "Digital Gold: Bitcoin and the Inside Story of the Misfits and Millionaires Trying to Reinvent Money" as well as "The Trolls of Wall Street: How the Outcasts and Insurgents Are Hacking the Markets." He has worked as a reporter for The New York Times, The Los Angeles Times and The Forward.