Beijing-based ByteDance 2017 acquisition of tween and teen-focused social app Musical.ly is paying off.

The company this year merged Musical.ly with its own short video app TikTok as a means of entering the U.S.

market.

Today, the result of that merger is sitting at the top of the U.S.

App Store, ahead of Facebook.

More importantly, it recently surpassed Facebook, Instagram, YouTube and Snapchat in monthly installs for the first time in September. According to data from app intelligence firm Sensor Tower, TikTok installs were higher than those of Facebook, Instagram, Snapchat and YouTube in the U.S.

last month. It surpassed the four other apps in terms of daily downloads on September 29, with 29.7 percent the downloads from this cohort of apps, the firm says. Since then, it has continued to increase its market share among this group of apps, reaching as high as 42.4 percent of downloads among the apps just days ago, on October 30. In September, TikTok installs grew around 31 percent from the prior month to reach approximately 3.81 million on the App Store and Google Play combined.

This beat No.

2 Facebook, which had 3.53 million first-time installs. Year-over-year, TikTok U.S.

installs were up 237 percent from 1.13 million in October 2017. As floods of new users join TikTok, the app has also flirted with passing some of these leading social apps in the App Store Top Charts, at times, too.

Today, it ahead of Facebook (No.

7) and Messenger (No.

5) as it sits in the No.

4 position, for example.

But it behind YouTube (No.

1), Instagram (No.

2) and Snapchat (No.

3). However, at other times it gotten as high as No.

3 in the Overall Free Apps Top Chart, according to App Annie data. App researcher Apptopia reports similar findings, in terms of TikTok surge.

However, it noted that the app engagement rates (the portion of monthly users who open the app daily) was still behind the rest of the group.

Apptopia said TikTok had a 29 percent engagement rate, compared with Facebook 96 percent, Instagram 95 percent, Snapchat 95 percent and YouTube 95 percent. It also noted the app gains have come, in part, from increased ad spend across Facebook, Google mobile ad platform AdMob, in-app ad platform Vungle and others.

Other gains are attributed to the merger. In June, TikTok (known as Douyin in China) reported reaching a global monthly active user count of 500 million across 150 countries and regions, which is around the time when Instagram reached one billion monthly actives, for comparison sake.