The European Commission said it has opened an in-depth investigation to assess the proposed acquisition of Willis Towers Watson by Aon, under the EU Merger Regulation.

Aon’s $30 billion bid for Willis Towers Watson to create the world’s largest insurance broker is now facing a five-month long probe after EU antitrust regulators voiced concerns that the deal may hurt competition in key markets.

Aon and Willis Tower Watson are both insurance and re-insurance brokers, as well as providers of other professional services to corporate customers.

Executive Vice-President Margrethe Vestager, responsible for competition policy, said: “Aon and Willis Towers Watson are two leading companies in the market for insurance and re-insurance brokerage.

“They help companies with their risk management and with finding the right insurers for their needs. 

“We have opened an in-depth investigation to assess carefully whether the transaction could lead to negative effects for competition, less choice and higher prices for European customers in the commercial risk brokerage market.”

Aon and Willis Towers Watson are both leading companies in the markets for commercial risk brokerage services, re-insurance brokerage and provision of retirement and health and welfare services to commercial customers.

The Commission said it is concerned that the proposed transaction could significantly reduce competition in those markets.

The Commission’s initial market investigation identified a number of concerns in relation to the supply of commercial brokerage services especially to large multi-national customers, who depend on brokers with a high level of expertise and a global presence.