ISS, one of the world's largest employers with more than 200,000 clients in 63 countries, posted an operating loss of 785 million Danish crowns in the quarter, down from a 1.42 billion crown profit a year earlier.

Its shares have fallen by around one-third this year and were trading 6.3% lower at 0713 GMT, the biggest loser on Europe's Stoxx 600 index.

ISS has grown from a cleaning business into a global operation, with services ranging from call centres to office cleaning, catering and security.

(Reporting by Jacob Gronholt-Pedersen, editing by Louise Heavens)