Marcus joined Harper’s as deputy editor in 2010 and was promoted to executive editor in 2013. During his tenure at the 165-year-old monthly magazine, he has edited feature articles, fiction and commentary.

Rosenbush was appointed interim editor of Harper's Magazines after Christopher Cox was fired in January 2016 by MacArthur, just three months into the job.

At the time, Cox told The New York Times that he had been dismissed because of “editorial differences with the publisher.” Harper’s is a nonprofit publication largely supported by MacArthur’s personal wealth, giving him considerable influence and editorial control.

Rosenbush had served as editor since 2010 after MacArthur fired Roger D. Hodge. She will serve as interim editor until Marcus takes his place in June.

Before he steps into his new role, Marcus is completing a book, Glad to the Brink of Fear: A Portrait of Emerson in Fourteen Installments. He is also editing The Journals of Ralph Waldo Emerson: A Selection." Both books are scheduled to be published next year.

Marcus has also contributed to a plethora of publications, such as as The New York Times Book Review, The Los Angeles Times Book Review, The Atlantic, Salon and The Village Voice.

From 2007 to 2010, he was editor-at-large at the Columbia Journalism Review.

Marcus served as senior editor at Amazon.com from 1996 - when the retailer was a startup - until 2001. His first book, Amazonia: Five Years at the Epicenter of the Dot-Com Juggernaut, is based off his experiences as Amazon’s 55th employee.