Construction giant Leighton may sell some of its businesses as part of measures to simplify its complex structure and grow profit.
The changes could result in job losses, with Leighton saying it wants to reduce costs and remove bureaucracy.
The company employs about 53,000 people, excluding contractors.
A spokesman said it was too early to provide details on how the changes would impact staff.
The global construction and engineering company has many subsidiaries that carry out similar work.
Its new management have decided to remove that duplication and focus on its key activities - construction, mining, engineering and public private partnerships.
Options are being reviewed for the John Holland and Leighton Services and Property businesses, which include sales or the introduction of new business partners, chief executive Marcelino Fernandez Verdes said.
Final decisions are yet to be made, however.
"By reorganising these activities we will create economies of scale, thereby lowering our cost base and helping to improve our competitive advantage and create value for the benefit of all stakeholders," he said.
Mr Fernandez Verdes has been leading a review of Leighton's business since taking the top job in March.
He is also the head of Germany-based, Spanish-owned construction company Hochtief, which recently increased its control of Leighton.