By Katie Paul in New York City

WITH Twitter already on the ropes, Meta’s Mark Zuckerberg has delivered another blow to Elon Musk, ramping up the tech billionaires’ rivalry with the launch of Instagram’s much-anticipated companion service Threads, a challenger to Twitter.

“Let’s do this. Welcome to Threads,” Zuckerberg wrote on Thursday in his first post on the app, along with a fire emoji.

He said the app logged five million sign-ups in its first four hours.

Much like Twitter, the app features short text posts that users can like, re-post and reply to, although it does not include any direct message capabilities.

Posts can be up to 500 characters long and include links, photos and videos up to five minutes long, according to a Meta blog post.

It is available in more than 100 countries on both Apple’s App Store and Google’s Play Store, the blog post said.

Analysts said investors were salivating over the possibility Threads’ ties to Instagram might give it a built-in user base and advertising apparatus.

That could siphon ad dollars from Twitter at a time when the microblogging company’s new CEO is trying to revive its struggling business.

While Threads launched as a standalone app, users can log in using their Instagram credentials and follow the same accounts, potentially making it an easy addition to existing habits for Instagram’s more than two billion monthly active users.

Threads’ arrival comes after Zuckerberg and Musk have traded barbs for months and even threatened to fight each other in a real-life mixed martial arts cage match in Las Vegas.

The timing is opportune for Meta to land a blow, as months of Musk’s chaotic decision-making has roiled Twitter.

Twitter has faced an exodus of advertisers amid deep staffing cuts and content moderation controversies.

Its latest move involved limiting the number of tweets users can read per day.

Zuckerberg, in subsequent Threads posts, addressed those challenges.

“I think there should be a public conversations app with 1 billion+ people on it,” he wrote.

Twitter has had the opportunity to do this but hasn’t nailed it. Hopefully we will.”

The integration with Instagram included several nods to privacy considerations.

Instagram users who sign up for Threads automatically have a badge affixed to their Instagram profile, but can opt to hide it.

They also are given options to choose different privacy settings for each app.

Brands such as Billboard, HBO, NPR and Netflix had accounts set up within minutes of launch, as had celebrities including Shakira and other well-known personalities such as former Meta chief operating officer Sheryl Sandberg.

The app did not appear to show any ads, according to a Reuters review.

Jasmine Enberg, principal analyst at Insider Intelligence, said Meta only needs to convince a quarter of Instagram’s users to join Threads to rival Twitter’s size.

“The reality is that Meta doesn’t need to convert Twitter power users into Threads users” to succeed, she said.

Zuckerberg, responding to a user who predicted Twitter’s demise about an hour after the Threads launch, cautioned patience.

“We’re only in the opening moments of the first round here,” he said.

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