Global CEO advisory firm Teneo, which was founded in Ireland, has bought WestExec Advisors, an advisory firm based in Washington, DC.
In a statement, it said it had acquired a majority stake in the business for an undisclosed sum.
The move follows Teneo's minority investment in the company last year, and marks the latest phase of its ongoing expansion.
WestExec, which was founded in 2017, provides a range of services including strategic counsel, geopolitical risk analysis, capital advisory, and counsel on international economics and regulatory issues.
It will continue to operate as an independent brand working in close partnership with the Teneo team.
"Now, more than ever, business leaders around the world are faced with a constant barrage of geopolitical, economic, social and market disruption that impact their operations, valuations and reputations," said Paul Keary, CEO of Teneo.
"The deepening of our relationship with WestExec through this transaction will keep Teneo at the forefront of these conversations with CEOs and their teams around the world," he added.
Mr Keary said Teneo and West Exec have worked together in the past, and now have ambitious plans to further scale the business.
Michèle Flournoy, Co-Founder and Managing Partner of WestExec said the investment will allow the team to build a larger advisory platform and scale their offerings.
"It will also further enable us to continue to deliver the highest quality strategic advice and support to our growing client base," Ms Flournoy said.
Wachtell, Lipton, Rosen & Katz served as legal advisors to Teneo on the transaction.
Holland & Knight served as legal advisors to WestExec on the transaction.