By Christine Ji

Muse is gaining popularity and helping convince investors that Meta's AI bets are paying off

As of Monday, the Muse app is sitting at the top of Apple's U.S. App Store.

Meta's stock is having a month to remember as the Facebook parent's artificial-intelligence assistant gains steam.

Shares of Meta (META) surged 11.4% on Monday, reaching their highest close since October 2025 and their largest daily percentage increase since April 2025. The momentum is being driven in large part by Meta's newly launched personal AI assistant, Muse, which recently claimed the top spot on Apple's (AAPL) U.S. App store.

Meta CEO Mark Zuckerberg has branded his company's AI strategy as a quest for "personal superintelligence" - technology that knows the user deeply and is highly customizable. Investors are getting a better idea of what that looks like with Muse.

Introduced on Sept. 8, Muse specializes in executing multistep tasks such as finding data across various accounts, filling out web forms, and negotiating and making online purchases. Users can query the agent on the Muse app or through WhatsApp.

The Muse craze has sent shares of Meta toward their best monthly run in over 13 years. The stock is up 29.5% since the beginning of the month and up more than 40% from its 52-week low in March, when investors reacted negatively to Meta's increased 2026 spending projections.

Concerns that Meta is spending unsustainably on AI have hung over the stock in recent months. This year, the company is on track for between $130 billion and $145 billion in capital expenditures, or spending on physical assets such as data centers. While Meta's traditional advertising business has been growing rapidly, investors were uncertain whether the company could open up new revenue opportunities with AI.

Now the success of Muse is easing some concerns about Meta's spending levels and helping convince investors that the company's AI monetization strategies will pan out. The basic Muse app is free for users, with additional paid tiers charging $20 and $100 a month.

Other monetization opportunities that intrigue Wall Street include the company's newly introduced Meta Model API, which marks the first time Meta has charged developers and enterprise users for access to its underlying models.

Still, challenges to widespread adoption remain as agents run into issues executing actions across different platforms. Over the weekend, Amazon.com (AMZN) blocked Muse from shopping on the website, citing a violation of its terms of use and security concerns.

"We believe this pressure is likely to broaden as agentic AI increasingly replaces human search, comparison and routine decision making," Pivotal Research Group analyst Jeff Wlodarczak wrote in a Monday note. Widespread use of AI agents could strike a blow to digital advertising businesses, Wlodarczak added, which could lead companies like Amazon to take action and develop first-party agents of their own.

The Meta Connect conference on Wednesday could be a further catalyst for the company's stock as Meta provides updates about new AI launches.

-Christine Ji

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09-21-26 1801ET