ISS A/S (International Service System) is a Facility Services company founded in Copenhagen, Denmark in 1901. ISS services include: cleaning services, support services, property services, catering services, security services and facility management services.
The ISS Group’s revenue amounted to DKK 73.5 billion in 2018 and ISS has nearly 500,000 employees and activities in approximately 65 countries across Europe, Asia, North America, Latin America and Pacific. More than half of ISS' employees are based in emerging markets.
1901 ISS was founded in Copenhagen, Denmark as a small security company with 20 night watchmen named København-Frederiksberg Nattevagt (Copenhagen-Frederiksberg Night Watch)
1934 ISS entered the cleaning business with the establishment of Det Danske Rengørings Selskab (The Danish Cleaning Company) as an independent subsidiary of the security company
1946 The first geographical expansion outside Denmark: Swedish subsidiary established
1968 The company adopted the ISS name
1973 Overseas expansion started
1975 Group revenue reached DKK 1 billion
1977 ISS shares listed on the Copenhagen Stock Exchange
1989 The total number of employees in the Group reached 100,000
1999 ISS acquired Abilis, the second largest European provider of cleaning and specialised services, in a DKK 3.6 billion acquisition, the Group’s largest ever.
Abilis had about 50,000 employees and annual revenues of DKK 5.2 billion in 1998.
The total number of employees in the Group reached 200,000
2003 ISS’ first major pan-European Integrated Facility Services contract signed
2005 ISS A/S was acquired by funds advised by EQT Partners and Goldman Sachs Capital Partners, and de-listed from the Copenhagen Stock Exchange.
The total number of employees in the Group reached 300,000
2006 Group revenue passed DKK 50 billion. ISS made the second-largest acquisition in company history, when acquiring the outstanding 51% of the shares in Tempo Services in Australia
2007 Group revenue passed DKK 60 billion. ISS entered the US market through the acquisition of Sanitors Inc.
Initial Public Offering (IPO) Process
The total number of employees in the Group reached 400,000
2008 ISS’s largest ever international Integrated Facility Services contract was signed
2010 Group revenue passed DKK 70 billion. The total number of employees in the Group reached 500,000 
2011 British security company G4S announces it will acquire ISS in a deal worth £5.2 billion. The deal is later shelved, owing to shareholder unrest 
2012 Ontario Teachers' Pension Plan (Teachers') and KIRKBI Invest A/S make EUR 500 million investment in ISS 
2014 ISS lists on the OMX Nasdaq Copenhagen Stock Exchange in Denmark’s biggest IPO in two decades 
2016 ISS enters a commercial agreement with IBM to use IBM Watson's Internet of Things platform to transform the management of over 25,000 buildings around the world.
2017 ISS signs the largest customer agreement in its history, with Deutsche Telekom, covering approximately 9,000 sites across Germany, more than 6,000 employees and about 4% of Group revenue.
In January 2016, ISS announced that it had acquired the UK, Ireland, and European activities of UK-based GS Hall, a technical services company focused on mechanical and electrical engineering, energy management, and compliance.
In November 2016, ISS announced that it had acquired Chile's fourth largest catering company, Apunto, with an annual revenue of DKK 116 million in 2015.
In April 2017, ISS announced that it had acquired US catering services company Guckenheimer with an annual revenue of approximately DKK 2,300 million and 3,200 employees in 33 US states.