Reddit on Tuesday reported a more than $500 million quarterly loss in its first earnings report as a public company, largely due to stock-based compensation expenses incurred during its initial public offering in March.

But the social media company also posted robust revenue and user growth, underscoring the potential of its digital advertising business as people flock to the site. Last month, Google, Meta and Snap also reported rising advertising sales and double-digit revenue growth.

Reddit’s revenue was $243 million in the first quarter, up 48 percent from $163.7 million a year earlier and above Wall Street estimates of $214 million, according to data compiled by FactSet. The net loss was $575.1 million, compared with a loss of $60.9 million a year earlier. Stock-based compensation expenses totaled $595.5 million, versus $13.2 million a year earlier.

Daily active users jumped to 82.7 million, up 37 percent from a year earlier.

“We see this as the beginning of a new chapter as we work toward building the next generation of Reddit,” Steve Huffman, Reddit’s co-founder and chief executive, said in a statement.

Reddit, which went public after more than 18 years as a private company, has turned into a kind of litmus test for technology initial public offerings. The company successfully debuted in what had been a tepid I.P.O. market, with its shares soaring 48 percent on the first day of trading and giving investors cause for optimism. Reddit’s shares continue to trade above the company’s I.P.O. price of $34.

Essentially a message board where users congregate on forums to research and discuss interests they have in common, Reddit has spent years trying to diversify its main business of digital advertising. It has struck deals with Google and other companies that wish to license its vast amounts of conversation data, such as for building artificial intelligence technology. It has also tried to spur an e-commerce business.

Reddit projected $240 million to $255 million in revenue in the current quarter, above Wall Street’s expectations.

TikTok sued the federal government on Tuesday over a new law that would force its Chinese owner, ByteDance, to sell the popular social media app or face a ban in the United States, stoking a battle over national security and free speech that is likely to end up in the Supreme Court.

TikTok said the law violated the First Amendment by effectively removing an app that millions of Americans use to share their views and communicate freely. It also argued that a divestiture was “simply not possible,” especially within the law’s 270-day timeline, pointing to difficulties such as Beijing’s refusal to sell a key feature that powers TikTok in the United States.

“For the first time in history, Congress has enacted a law that subjects a single, named speech platform to a permanent, nationwide ban, and bars every American from participating in a unique online community with more than one billion people worldwide,” the company said in the 67-page petition, which initiated the lawsuit. “There is no question: The act will force a shutdown of TikTok by Jan. 19, 2025.”

TikTok is battling for its survival in the United States, with the fight set to play out primarily in courts over the next few months. The battle pits Congress’s national security concerns about the social media app’s ties to China against TikTok’s argument that a sale or ban would violate the First Amendment free-speech rights of its users and hurt small businesses that owe their livelihood to the platform. The case is expected to reach the Supreme Court.

The issue is particularly tricky in an election year, when President Biden and lawmakers are facing potential blowback from users of the popular app. The app, which says it has 170 million monthly users in the United States, is used for everything from sharing viral dances to political commentary. It’s become knitted into people’s lives, particularly for those who make a living on the platform as content creators.

Under the new law, which President Biden signed on April 24, TikTok has nine months, or a year if the president gives it an extension, to find a non-Chinese buyer. If it doesn’t, the law requires U.S. app stores and web hosting services to stop working with it — essentially banning it.

At the heart of the case will be lawmakers’ intent to defend the United States from what they and some experts say is a national security threat; they assert that the Chinese government could lean on ByteDance to turn over sensitive TikTok user data or use the app to spread propaganda. But the mandate to sell or block the app could result in changes to TikTok’s content policies and shape what users are able to freely share on the platform, potentially violating their free speech rights, according to legal experts.

“These are hugely consequential questions being dealt with in an unprecedented manner,” said Evelyn Douek, an assistant professor at Stanford Law School who has done research on the First Amendment and the internet. “TikTok basically throws the First Amendment sink at this challenge.”

TikTok filed its suit in the U.S. Court of Appeals for the District of Columbia Circuit, arguing that selling its U.S. operations was not “commercially, technologically, or legally feasible.” A part of that argument hinges on how TikTok and its competitors are global in nature and content is accessible across country borders, with international videos as part of its appeal.

It is also impossible to move the app’s underlying coding to a new owner, TikTok argued, adding that it would take years for a new set of engineers to familiarize themselves with that code to develop and maintain the platform. In addition, the engineers would need access to ByteDance software to keep TikTok functioning, which the new law prohibits, the company argued.

TikTok’s success also hinges on its recommendation algorithm, which helps surface tailored content to users, something the Chinese government has said it would not sell, the suit notes.

TikTok pointed to the billions of dollars it has already spent to address potential security risks in the past four years, an effort known as Project Texas, as well as a draft 90-page national security agreement that made “extraordinary” commitments to the U.S. government. TikTok has separated its U.S. user data from the rest of the company’s operations and provided third-party oversight of its content recommendations.

The company said in its suit that it agreed to give the government a “shutdown option” that would allow it to suspend TikTok in the United States if the company violated parts of its agreement.

Anupam Chander, a visiting scholar at the Institute for Rebooting Social Media at Harvard who has publicly opposed the law, said that he was among experts TikTok contacted on Monday for an advance briefing on the filing. He said Project Texas is likely to play a key role, and whether TikTok can persuade the judge that it was a reasonably available alternative that addressed the government’s concerns.

“The real question that remains that I haven’t seen an answer to is, what more would the government have wanted?” Mr. Chander said. “We’ve never heard why Project Texas was insufficient, publicly.”

National security concerns about TikTok are “speculative” and fall short of what’s required to justify violating First Amendment rights, the company argued in its suit, adding that President Biden and other members of Congress’s use of the platform undermines claims that it’s a threat.

TikTok asked the court to issue a declaratory judgment saying that the law violated the Constitution and to issue an order that would stop Attorney General Merrick B. Garland from enforcing it. The next step is for the government to respond.

A spokesman for the Department of Justice declined to comment on potential litigation.

The government is likely to defend the law by saying it is calling for a sale, not a ban. The government will probably also need to make a strong case that its national security concerns justify the limitation on speech if TikTok is banned.

The Justice Department, which was involved in drafting the law, weighed in on language that would help the Biden administration best defend it in court.

“They’re going to have to support their concerns with evidence in a way that they haven’t really done, at least in the court of public opinion, and they’re going to have to show that their concerns can’t be addressed in narrower ways,” Ramya Krishnan, a senior lawyer at the Knight First Amendment Institute at Columbia University, said in an interview before the petition was filed.

The institute expects to support a challenge to the law, she said. The American Civil Liberties Union has also said it opposed the law and may help with litigation.

TikTok’s suit was filed a day after its chief executive, Shou Chew, appeared with his wife at the Met Gala, where he was an honorary chair.

Fears of a potential security threat from TikTok have escalated in the last year and a half, prompting bans of the app on federal devices and those issued by some city and state governments. Still, the app has continued to grow in popularity, shaping culture and becoming a source of news for younger Americans as well as a place where an expanding cohort of content creators make their living.

TikTok has had success in challenging similar state and federal actions attempting to restrict its operations, though this law differs in its broad support from Congress and the Biden administration.

Last year, Montana passed a law that would have barred TikTok from operating in the state as of Jan. 1, saying the company presented a security threat to its citizens. A group of TikTok users filed a lawsuit funded by the app, saying the law violated their First Amendment rights and outstripped the state’s legal authority. TikTok also filed a separate lawsuit within a week, arguing that the legislation violated the First Amendment.

In November, a federal judge blocked the Montana ban, saying it most likely violated the First Amendment and a clause that gives Congress the power to regulate commerce with foreign nations.

Former President Donald J. Trump also tried to ban or force the sale of TikTok in 2020 with an executive order citing similar security concerns. Federal courts blocked the Commerce Department from carrying out his plan in part on First Amendment grounds, with one judge adding it would shut down a “platform for expressive activity.” Another judge said the government most likely overstepped its legal authority and “acted in an arbitrary and capricious manner by failing to consider obvious alternatives.”