[BBC]
How will it affect the future and course of Sun?
The 51-year-old will quit the post with immediate effect, but will stay on at the company in the role of chairman.
Sun's current president and chief financial officer Jonathan Schwartz will take over at the helm of the firm.
The news came as the US firm revealed third quarter losses had widened to $217m (£121.4m) from $28m at the same time a year ago.
How will it affect the future and course of Sun?