On Wednesday, the US Department of Justice filed a lawsuit aimed to prevent Aon (NYSE:AON), one of the leading global insurance brokers, from acquiring Willis Towers Watson in a $30 billion deal.
The acquisition would have combined the second-largest and third-largest of the "Big Three" global insurance brokers, the other being Marsh McLennan.
Aon and Willis hold at least 40% of the market share in several commercial insurance markets in the US, such as property damage and financial risk. The acquisition would have allowed Aon-Willis to overtake Marsh McLennan as the biggest firm in the insurance market.
The Justice Department outlined in the complaint that such a takeover would "...eliminate substantial head-to-head competition and likely lead to higher prices and less innovation, harming American business and their customers, employees, and retirees".
According to Merrick Garland, a US attorney-general, this lawsuit represents the Justice Department's commitment to "stopping harmful consolidation and preserving competition that directly and indirectly benefits Americans across the country".
Aon shares fell 3.1% on Wednesday, and Willis tumbled more than 7% to its lowest price in nearly two months. However, both companies remain steadfast to carrying through with the merger, as they announced their disagreement with the Department of justice's actions, stating that it "...reflects a lack of understanding of our business, the clients we serve, and the market places in which we operate".