Meta's AI companion Muse has surpassed 10 million U.S. downloads in its first 40 days, according to new data from market intelligence provider Sensor Tower. This milestone places it in an exclusive group of apps, including Meta's Threads, that have achieved similar post-launch scale. Sensor Tower's data also indicates Muse is retaining users at higher rates than its AI rivals like ChatGPT, Claude, and Grok, with a 30% 7-day retention rate and a 23% 14-day retention rate in the U.S. The app also hit 2.5 million daily active users for the first time on October 16, a 15% week-over-week increase. Meta has allocated 39% of its total advertising spend to market Muse in October, up from 23% last month.