Is Marsh & McLennan Cos., Inc. overvalued or undervalued?

As of 11 September 2025, the valuation grade for Marsh & McLennan Cos., Inc. has moved from fair to expensive, indicating that the stock is overvalued. The company exhibits a P/E ratio of 29, a Price to Book Value of 8.96, and an EV to EBITDA of 17.47, all of which suggest a premium valuation compared to its peers. In comparison, Aon Plc has a P/E of 29.25 and Arthur J. Gallagher & Co. has a significantly higher P/E of 45.99, reinforcing the notion that Marsh & McLennan is trading at elevated multiples relative to its industry.
The company's recent performance has lagged behind the S&P 500, with a year-to-date return of -7.66% compared to the index's 12.22%, and a one-year return of -13.28% versus 17.14% for the S&P 500. This underperformance further supports the conclusion that Marsh & McLennan is overvalued in the current market context.