<ul data-eligibleForWebStory="false">Former NBCU ad exec Linda Yaccarino improved X's ad business in her short tenure.Ad spending in the U.S. increased by 62% in the first half of 2025.Yaccarino's exit could impact X's profitability as it still faces challenges.X faced advertising downturn post-Musk takeover but later saw improvement under Yaccarino.