The authors thank the editor, the associate editor, two anonymous referees, Justin Birru, John Barrios, Kimball Chapman, Claudia Custodio, Rüdiger Fahlenbrach, Laurent Frésard, Todd Gormley, Justin Hopkins, Jared Jennings, Claudio Loderer, Swaminathan Kalpathy, Florian Peters, Anjan Thakor, Philip Valta, Alexander Wagner, Toni Whited, and the audience of the workshop at the University of Bern and SFI Research Days 2018 for helpful comments. The authors are grateful for excellent research assistance from Mengzhou Wang.