The numbers were nearly as bad worldwide, as daily active users on the mobile app fell to 174 million in February, down 15% from a year earlier, the firm said. The worldwide user base has been flat or down every month during Musk’s tenure began except one, when it grew slightly in October and then resumed falling, according to Sensor Tower. 

Other social media apps experienced modest increases in their worldwide user bases during the same period, according to the research, with Snapchat growing 8.8%, Instagram 5.3%, Facebook 1.5% and TikTok 0.5%. Those apps all experienced declines over that period in the U.S., but none was as steep as the decline on X. 

X had “the most material decline in active users compared to its peers,” Abe Yousef, a senior insights analyst at Sensor Tower, wrote in a research report. 

“This decline in X mobile app active users may have been driven by user frustration over flagrant content, general platform technical issues, and the growing threat of short-form video platforms,” he wrote. 

Under Musk’s ownership, X has relaxed content moderation rules that previously limited hateful content, such as white supremacist imagery, and Musk has welcomed back to the platform some users whom the old Twitter management had banned. In December, he reinstated the accounts of conspiracy theorist Alex Jones and his Infowars website and then held a public audio-only event with Jones. 

X said in a post Monday that the worldwide number is higher than what Sensor Tower data shows, with 250 million people using X every day globally. That would still be a decrease from when Musk bought the app. Musk said in 2022 that, at about the time he completed the purchase in late October, Twitter had about 258 million “monetizable daily active users,” the company’s metric at the time. 

X didn’t respond to a request for additional information. It didn’t say how it defines who counts as an active user — a metric that by its name may appear straightforward but that tech platforms define differently. 

On a monthly basis, X has 550 million people using it, according to the company. That figure represents growth of 1.5% since July, when Musk said X had 542 million monthly users. 

Sensor Tower defines a daily active user as someone who “registered a session of at least two seconds in length, once in that day.” It says its data comes from a panel of consumers who provide access to their information in exchange for the use of other apps, including apps that track screen time. 

Advertisers have also left X, Sensor Tower said, with 75 out of the top 100 U.S. advertisers on X from October 2022 having ceased ad spending on it. The exodus spiked toward the end of last year, after Musk publicly embraced an antisemitic conspiracy theory and told advertisers at a conference in New York, “Go f— yourself.” 

In recent days, Musk has urged his 177 million followers on X to get more people onto the platform. On Sunday, he posted instructions for how to share posts with friends, a basic function of social media. 

“Please send links from this platform to your friends who are still being misled by the legacy media!” he wrote in a separate post Sunday. 

Musk has also shifted the platform’s business model from being almost entirely ad-supported to one that also has four subscription tiers, from free to a Premium+ service that starts at $16 a month. 

Sensor Tower said that, according to its research, X’s revenue from in-app purchases last month was about $9.5 million, including for X subscriptions and payments to creators. 

“This still remains just a fraction of revenue that the company was previously generating from advertising in its last year as a public entity,” Yousef wrote. Twitter in July 2022 reported $1.18 billion in revenue for the previous three months. 

X has been helped by the lack of a clear text-based social media alternative. Threads, a competitor launched by Instagram and its parent company, Meta, had 1.6 million daily active U.S. mobile users in February, according to Sensor Tower, and 14 million worldwide. 

Threads has a potential major advantage over other upstart apps because it is closely integrated with Instagram — users of Instagram can see Threads posts in their feeds and create accounts relatively easily. That has translated into a whopping disparity in downloads, according to a second research firm, Apptopia, based in Boston, which said Threads beat X in downloads worldwide by an 8-to-1 ratio in February. 

Downloads were even more lopsided in the U.S. in February, with Threads getting about 16 downloads for every one download of X, Apptopia said. 

“For microblogging platforms, X had dominant market share of app downloads right up until Threads launched,” Tom Grant, vice president of research at Apptopia, wrote in an email. “That turned market share completely on its head.” 

There were 2.9 million downloads of X in the U.S. in February, up 14% from a year earlier but still below the 3.7 million in October 2022, the month Musk bought the company, according to Apptopia. Threads had 46.2 million downloads last month, Apptopia said. 

Threads has ranked highly in some app store rankings lately, topping Apple’s chart for free apps Sunday and staying in the Top 4 for most of this week. X ranked No. 34 on the Apple app store Sunday and No. 30 on Friday. On Friday, Threads ranked No. 7 in Google’s Play store and X ranked No. 43.

But so far, the downloads haven’t translated into sustained growth for Threads, according to Sensor Tower. Another X competitor, Bluesky, was even smaller, with 195,000 U.S. daily active mobile users in February, according to the research firm. 

In its own data summary published Monday, X said that “1.7 million people join X every day.” That number is roughly triple the number of daily X downloads worldwide, according to Apptopia, and it suggests that X is growing at a rate of nearly 10% per month — far faster than any other source indicates.