 RALEIGH, N.C., April 19, 2021 GLOBE NEWSWIRE -- Martin Marietta Materials, Inc. NYSE:MLM Martin Marietta or the Company today announced that it will provide an online Web simulcast of its first-quarter 2021 earnings conference call on Tuesday, May 4, 2021. The Company will release results for the quarter ended March 31, 2021, that morning before the market opens. 