The merger, which has been approved by the boards of both companies, will see a new entity named Willis Towers Watson listed on the New York Stock Exchange.
The union of Towers Watson and Willis Group is expected to deliver cost synergies of US$100-$125 million to shareholders, according to a joint statement by the companies.
"The combination of Willis and Towers Watson brings together two highly complementary businesses to create an integrated global advisory, broking, and solutions provider to serve a broad range of clients in existing and new business lines," said the statement.
"The combined company will have approximately 39,000 employees in over 120 countries, and pro forma revenue of approximately $8.2 billion and adjusted/underlying EBITDA of over $1.7 billion for the 12 months ended 31 December 2014."
Towers Watson chairman and chief executive John Haley described the merger as a "tremendous combination of two highly compatible companies".
"We see numerous opportunities to enhance our growth profile by offering integrated solutions that leverage Willis’ global distribution network and superb risk advisory and re/insurance broking capabilities to deliver a more robust set of analytics and product solutions across a broader client base, including accelerating penetration of our Exchange Solutions platform into the fast growing middle-market," Mr Haley said.
"We also expect to realise substantial efficiencies by bringing our two organisations together, and have a well-defined integration roadmap to capitalise on identified savings, ensure the strongest combination of talent and practices, and realise the full benefits of the merger for all of our stakeholders."
