UPDATE 1-ATM machine-maker Diebold's CEO steps down

(Adds background on Mattes, company forecast)

Dec 13 (Reuters) - Diebold Nixdorf Inc, one of the world's largest ATM makers, said on Wednesday that President and Chief Executive Andreas Mattes is stepping down, effective immediately.

Diebold said Chief Financial Officer Christopher Chapman and Chief Operating Officer Juergen Wunram will serve as interim co-presidents and co-CEOs.

Mattes, who served as CEO for slightly over four years, was behind Diebold's $1.9 billion takeover of Wincor Nixdorf in 2016, which gave the combined company a market share of about 35 percent. http://reut.rs/2AzurIn

Diebold said its board has formed a search committee and retained executive search firm Heidrick & Struggles to find new CEO.

The company also reaffirmed its full-year 2017 revenue forecast of about $4.6 billion and adjusted earnings forecast of $1.05-$1.15 per share. (Reporting by Nikhil Subba in Bengaluru; Editing by Savio D'Souza)