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MarshMcLennan NEWS RELEASE Exhibit 99.1 Marsh McLennan 1166 Avenue of the Americas New York , New York 10036-2774 212 345 5000 www.mmc.com MARSH MCLENNAN REPORTS FIRST QUARTER 2021 RESULTS First Quarter Revenue Growth of 9 % Including Underlying Revenue Growth of 6 % First Quarter GAAP EPS of $ 1.91 ; Adjusted EPS Increases 21 % to $ 1.99 GAAP Operating Income Rises 27 % ; Adjusted Operating Income Increases 20 % NEW YORK , April 27 , 2021 – Marsh McLennan ( NYSE : MMC ) , the world's leading professional services firm in the areas of risk , strategy and people , today reported financial results for the first quarter ended March 31 , 2021 . Dan Glaser , President and CEO , said : “ Marsh McLennan had an outstanding first quarter . We delivered strong growth in underlying revenue and adjusted earnings , and generated meaningful adjusted operating margin expansion in both Risk & Insurance Services and Consulting . Our total revenue grew 9 % , with underlying revenue growth of 6 % . Adjusted operating income rose 20 % , adjusted EPS grew 21 % , and our adjusted operating margin increased 260 basis points to 29.6 % . " Our excellent start to 2021 positions us well for the balance of the year . " Consolidated Results Consolidated revenue in the first quarter of 2021 was $ 5.1 billion , an increase of 9 % , or 6 % on an underlying basis , compared with the first quarter of 2020. Operating income was $ 1.4 billion compared with $ 1.1 billion in the prior year . Adjusted operating income , which excludes noteworthy items as presented in the attached supplemental schedules , rose 20 % to $ 1.4 billion . Net income attributable to the Company was $ 983 million , or $ 1.91 per diluted share , in the first quarter . This compares with $ 754 million , or $ 1.48 per diluted share , in the prior year . Adjusted earnings per share rose 21 % to $ 1.99 compared with $ 1.64 for the prior year period . 1