Muse Beat ChatGPT to 5 Million Downloads. Meta Owns the Billboards.

Meta’s Muse reached 5 million U.S. downloads in 22 days. Sensor Tower’s numbers, reported by 9to5Mac, put ChatGPT at 56 days for the same milestone, Grok at 103 and Claude at 492. Sensor Tower says only 23 apps have ever passed 5 million U.S. downloads within 22 days of launch. About 85% of them are games like Fortnite and Pokémon GO. The other three are Disney+, HBO Max and Threads.

The Sensor Tower note also included a second number. Muse “has received the largest share of Meta’s house ads, accounting for up to 50% of daily house impressions” between Sept. 14 and Sept. 27, “as Facebook and WhatsApp ceded share.” Meta, it said, “began to ramp advertising spend for Muse on Wednesday, September 16, 2026, as downloads spiked 73% DoD.”

So how much of the record belongs to the product, and how much to the fact that its maker owns the billboards? The honest answer is less clean than a headline wants. That’s also why the question is worth asking.

Two timelines

The case for Muse being a real hit is strong, and some of it comes from the same analytics firm. Meta launched the agent on Sept. 8 as a free app with optional paid plans. It can do tasks on your behalf, keep working after you close it and ask you before sensitive actions like sending an email or making a purchase. TechCrunch, citing Sensor Tower, reported that Muse averaged 55% day-over-day download growth from Sept. 8 to Sept. 17. ChatGPT averaged 24% over its first 10 days. Muse hit No. 1 on the U.S. App Store on Sept. 18 and on Google Play on Sept. 19. Bloomberg’s Sept. 21 headline said it was drawing strong early reviews.

TechCrunch’s Sarah Perez made the counterargument herself: “Muse’s growth can’t be chalked up to Meta’s marketing efforts alone, as ads promoting the app only account for 6% of the ad impressions from launch through September 19.” In the same piece, she reported that Sensor Tower estimated 2.8 million downloads in the app’s first two weeks.

Now the second timeline, from the same data. Meta started running house ads for Muse on Sept. 9, the day after launch. Within 10 days, Muse was getting most of Meta’s in-house promotion, ahead of Facebook, Instagram and WhatsApp. The paid push started Sept. 16. By Sept. 22, Sensor Tower ranked Muse among the top 10 brands by ad spend, and in the week of Sept. 21–27 it was among the top 15 U.S. brands by impressions. Muse took the No. 1 spot two days after the paid ramp. Its share of house ads reached up to half of daily impressions between Sept. 14 and Sept. 27, which covers most of its climb past 3 million downloads.

Our read is that Muse earned its opening and Meta paid for the finishing line. The early curve is real. The record was measured at 22 days, and those 22 days include the period when Meta promoted Muse hardest. Downloads also aren’t users. None of the published reports include retention figures. The only engagement number TechCrunch reported is that daily actives rose 27% the day after Meta Connect.

The Threads precedent

Look at the non-game company Muse joined on that list. Disney+, HBO Max and Threads each launched into an audience it already had. Threads, the Meta one, required an Instagram account and let users carry over their follows. It reached 100 million sign-ups in five days in July 2023. Within a month, daily active users had fallen more than 80%.

Threads recovered and built a lasting product, so the precedent cuts both ways. It does show what Meta’s distribution can do on day one, and how little it says about day 60. Meta knows the difference better than anyone. Connor Hayes, Meta’s head of Threads, told Business Insider, as quoted by TechCrunch, that promoting Muse needs “promotional units that can showcase something the AI agent can do for the user, based on Meta’s understanding of what would be useful or helpful to them specifically.” Our read is that the ads are personalized using what Meta already knows about you. That leads to the second Muse story from Sept. 30.

“Syncing his device notifications”

Inc. columnist Jason Aten reported that Muse’s Mac app read his private Messages even though he had Full Disk Access turned off, according to TechCrunch’s account of his report. When he asked Muse how, it said it had been syncing his device notifications. That would suggest it read message text from incoming banners.

Meta flatly disputed it. “The Messages integration in the Muse app for Mac is entirely opt-in,” spokesperson Andy Stone said. “You have to enable both Full Disk Access and the Messages connector for Muse to be able to read your Messages content.” David Singleton of Meta Superintelligence Labs wrote on Threads that access requires “three separate steps of application-level permissions and built-in macOS system-level protections.” He said those protections “can’t be circumvented even if the Muse application had a bug.” He also said the agent’s own explanation was wrong.

That last point is the strange part of Meta’s defense. Meta’s position is that its agent gave a user a false account of its own behavior. Perez’s conclusion was blunt: “If anything, the company should be engaging with the journalist directly to determine how this could have possibly happened, instead of just denying that it did.”

We agree, and Meta has given itself the means to do it. Its launch post promised that Muse keeps “a complete audit trail of everything it has done and plans to do.” If that trail exists for Aten’s account, it can settle the question either way. If Singleton is right, the log clears the app and shows where the agent’s wrong explanation came from. That’s worth knowing for a product that runs while you’re away.

There’s a fair caveat. In a separate incident, YouTuber Matt Robb said Muse exposed his address while handling a Facebook Marketplace task. TechCrunch updated its story to note that Robb later acknowledged granting permissions that enabled it. Not every agent mishap turns out to be the agent’s fault.

Both stories point to the same issue. Meta can give Muse up to half its house-ad inventory on Facebook and WhatsApp, and no other AI company has that kind of reach. Whether those people keep using it depends on whether they believe the agent’s account of what it did on their computer.

Sources

• 9to5Mac: Meta's Muse crosses 5 million downloads amid massive advertising push
• TechCrunch: Meta is putting its muscle behind Muse as the AI app takes off
• TechCrunch: Meta disputes claim that Muse read a user's private messages without permission
• Bloomberg: Meta's new Muse AI app tops charts, draws strong early reviews
• Meta Newsroom: Introducing Muse, a personal AI agent
• Meta Newsroom: Muse for Small Business
• Wikipedia: Threads (social network)