Olson was formerly a subsidiary of Skanska. The firm specialises in high quality fit out and M&E maintenance services for international companies.
Olson was sold to private investors by Skanska in 2006.
ISG signed a joint venture agreement with Olson in March 2009 to boost turnover in Eastern Europe and to date has successfully collaborated with Olson on three projects for multinational clients.
Olson’s turnover in 2009 was £6m and it employs 125 people.
ISG has acquired the entire share capital of Olson for a nominal amount and agreed to invest up to £800,000 in working capital to refinance existing vendor loans and to support Olson’s future growth.
David Lawther, Chief Executive of ISG, said: “Acquiring Olson demonstrates ISG’s commitment to provide a high quality service to our multinational clients in Moscow, an important and expanding market for them.
“Olson’s considerable experience and knowledge of the local supply chain has already benefited clients and we plan to be able to expand the depth and range of their services.”