On Tuesday, Make Sunsets announced it had completed three balloon launches near Reno, Nevada, each of which contained less than 10 grams of sulfur dioxide, which is the most commonly sited aerosol particle discussed in conversations about solar geoengineering. Two of the balloons launched also had location trackers, and one had a camera, too.
The idea of solar geoengineering has been around for decades and generally refers to spraying aerosol particles into the upper atmosphere in order to reflect the sun’s rays away from earth and back to space, cooling the earth and temporarily mitigating the effects of climate change.
Essentially, solar geoengineering is mimicking what happens when a volcano erupts, and it’s known to work. When Mount Pinatubo in the Philippines released thousands of tons of sulfur dioxide into the stratosphere in the 1991 eruption, the global temperature of the earth was lowered on average by about 1 degree Fahrenheit, according to the U.S. Geological Survey.
Solar geoengineering is not a solution to climate change, and nobody who studies it rigorously suggests it should be. It’s a temporary stopgap measure.
In addition, while releasing sulfur dioxide particles will cool the earth quickly and relatively inexpensively, it’s also dangerous. Injecting sulfur dioxide into the atmosphere could damage the ozone layer, cause respiratory illness and create acid rain.
But as the effects of climate change become more obvious, people are beginning to take the idea more seriously.
The White House is coordinating a five-year research plan into solar geoengineering, the quadrennial U.N.-backed Montreal Protocol assessment report included an entire chapter addressing stratospheric aerosol injection (more colloquially called solar geoengineering), and Dustin Moskovitz, a co-founder of Facebook, is funding solar geoengineering research via his philanthropic organization, Open Philanthropy.
While momentum is building, there isn’t any international governance rules about how to study and potentially regulate the idea.
Luke Iseman, a serial inventor and the former director of hardware at Y Combinator, launched Make Sunsets in October in an effort to push that envelope. San Mateo-headquartered venture capital firm BoostVC invested $500,000 in the startup and Iseman brought in a co-founder, Andrew Song.
The launches in Nevada earlier in February occurred at the Rancho San Rafael Regional Park in Reno, , where an annual hot-air balloon festival takes place, Iseman told CNBC.
They chose Nevada “because it’s in the U.S., we’re very confident we know and followed all applicable rules, know the terrain well from past adventures, and, we didn’t want to interfere with a friend’s efforts to get a marine cloud brightening project permitted in California,” Iseman told CNBC.
The Nevada launch was previously detailed by Time reporters, who were there. It was a shoe-string MacGyver-ed event orchestrated out of a hotel room, with a grill and weather balloon equipment. But, as evidenced by the images embedded below, shared with CNBC by Make Sunsets, the balloons lifted off.
Make Sunsets team is filling sulfur dioxide in a bag preparing for launch.
Photo courtesy Make Sunsets
Make Sunsets team is weighing the bag filled with sulfur dioxide gas in a bag preparing for launch.
Photo courtesy Make Sunsets
Make Sunsets is filling the balloon with helium here.
Photo courtesy Make Sunsets
Here, founder Luke Iseman is preparing to release the weather balloon filled with sulfur dioxide and helium into the atmosphere. Make Sunsets says this is the first deployment of SAI, or stratospheric aerosol injection, another and more specific name for solar geoengineering.
Photo courtesy Make Sunsets
Luke Iseman, the founder of Make Sunsets, is about to launch a weather balloon filled with sulfur dioxide and helium into the air in Nevada.
Photo courtesy Make Sunsets
Make Sunsets launching a weather balloon filled with sulfur dioxide and helium into the air in Nevada.
Photo courtesy Make Sunsets
A view from the Make Sunsets balloon launched in Nevada.
Photo courtesy Make Sunsets
A view from the Make Sunsets balloon launched in Nevada.
Photo courtesy Make Sunsets
Iseman has both idealistic and practical goals.
“Most importantly: We need to cool earth to save millions of lives, hundreds of thousands of species, and buy the time we need to decarbonize,” Iseman told CNBC.
To make the business sustainable, Make Sunsets is selling cooling credits, which gives companies and individuals a way to offset the effects of their carbon emissions. But the startup has yet to deliver.
“We have 2,790 cooling credits ordered by 58 paying customers that we haven’t yet delivered,” Iseman told CNBC. “On one hand, we’re working hard on a controversial project to cool earth. On the other, we’re a startup with the same basic challenge as any other: get customers to pay more for what we’re selling than it costs to make it.”
Make Sunsets said it made the FAA aware that it was releasing a balloon.
The FAA provided the following statement: “The FAA has comprehensive regulations for safely operating unmanned free balloons. Among other things, the regulations require the balloon to be equipped so it can be tracked by radar, and the operator to notify the FAA prior to and at the time of launch, monitor and record the balloon’s course, make position reports to the FAA as requested, and notify the FAA when the balloon begins its descent and its expected trajectory.”
Correction: A previous version of this story misstated what the balloons contained. All three of them had sulfur dioxide.
Circle, the company behind the USDC stablecoin, has filed for an initial public offering with the U.S. Securities and Exchange Commission.
The S1 lays the groundwork for Circle’s long-anticipated entry into the public markets.
While the filing does not yet disclose the number of shares or a price range, sources told Fortune that Circle plans to move forward with a public filing in late April and is targeting a market debut as early as June.
JPMorgan Chase and Citi are reportedly serving as lead underwriters, and the company is seeking a valuation between $4 billion and $5 billion, according to Fortune.
This marks Circle’s second attempt at going public. A prior SPAC merger with Concord Acquisition Corp collapsed in late 2022 amid regulatory challenges. Since then, Circle has made strategic moves to position itself closer to the heart of global finance — including the announcement last year that it would relocate its headquarters from Boston to One World Trade Center in New York City.
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Circle is best known as the issuer of USDC, the world’s second-largest stablecoin by market capitalization.
Pegged one-to-one to the U.S. dollar and backed by cash and short-term Treasury securities, USDC has roughly $60 billion in circulation.
Circle is best known as the issuer of USDC, the world’s second-largest stablecoin by market capitalization.
Pegged one-to-one to the U.S. dollar and backed by cash and short-term Treasury securities, USDC has roughly $60 billion in circulation. It makes up about 26% of the total market cap for stablecoins, behind Tether‘s 67% dominance. Its market cap has grown 36% this year, however, compared with Tether’s 5% growth.
Coinbase CEO Brian Armstrong said on the company’s most recent earnings call that it has a “stretch goal to make USDC the number 1 stablecoin.”
The company’s push into public markets reflects a broader moment for the crypto industry, which is navigating renewed political favor under a more crypto-friendly U.S. administration. The stablecoin sector is ramping up as the industry grows increasingly confident that the crypto market will get its first piece of U.S. legislation passed and implemented this year, focusing on stablecoins.
Stablecoins’ growth could have investment implications for crypto exchanges like Robinhood and Coinbase as they integrate more of them into crypto trading and cross-border transfers. Coinbase also has an agreement with Circle to share 50% of the revenue of its USDC stablecoin.
The stablecoin market has grown about 11% so far this year and about 47% in the past year, and has become a “systemically important” part of the crypto market, according to Bernstein. Historically, digital assets in this sector have been used for trading and as collateral in decentralized finance (DeFi), and crypto investors watch them closely for evidence of demand, liquidity and activity in the market.
More recently, however, rhetoric around stablecoins’ ability to help preserve U.S. dollar dominance – by exporting dollar utility internationally and ensuring demand for U.S. government debt, which backs nearly all dollar-denominated stablecoins – has grown louder.
A successful IPO would make Circle one of the most prominent crypto-native firms to list on a U.S. exchange — an important signal for both investors and regulators as digital assets become more entwined with the traditional financial system.
The Hims app arranged on a smartphone in New York on Feb. 12, 2025.
Gabby Jones | Bloomberg | Getty Images
Hims & Hers Health shares closed up 5% on Tuesday after the company announced patients can access Eli Lilly‘s weight loss medication Zepbound and diabetes drug Mounjaro, as well as the generic injection liraglutide, through its platform.
Zepbound, Mounjaro and liraglutide are part of the class of weight loss medications called GLP-1s, which have exploded in popularity in recent years. Hims & Hers launched a weight loss program in late 2023, but its GLP-1 offerings have evolved as the company has contended with a volatile supply and regulatory environment.
Lilly’s weekly injections Zepbound and Mounjaro will cost patients $1,899 a month, according to the Hims & Hers website. The generic liraglutide will cost $299 a month, but it requires a daily injection and can be less effective than other GLP-1 medications.
“As we look ahead, we plan to continue to expand our weight loss offering to deliver an even more holistic, personalized experience,” Dr. Craig Primack, senior vice president of weight loss at Hims & Hers, wrote in a blog post.
A Lilly spokesperson said in a statement that the company has “no affiliation” with Hims & Hers and noted that Zepbound is available at lower costs for people who are insured for the product or for those who buy directly from the company.
In May, Hims & Hers started prescribing compounded semaglutide, the active ingredient in Novo Nordisk‘s GLP-1 weight loss medications Ozempic and Wegovy. The offering was immensely popular and helped generate more than $225 million in revenue for the company in 2024.
But compounded drugs can traditionally only be mass produced when the branded medications treatments are in shortage. The U.S. Food and Drug Administration announced in February that the shortage of semaglutide injections products had been resolved.
That meant Hims & Hers had to largely stop offering the compounded medications, though some consumers may still be able to access personalized doses if it’s clinically applicable.
During the company’s quarterly call with investors in February, Hims & Hers said its weight loss offerings will primarily consist of its oral medications and liraglutide. The company said it expects its weight loss offerings to generate at least $725 million in annual revenue, excluding contributions from compounded semaglutide.
But the company is still lobbying for compounded medications. A pop up on Hims & Hers’ website, which was viewed by CNBC, encourages users to “use your voice” and urge Congress and the FDA to preserve access to compounded treatments.
With Tuesday’s rally, Hims and Hers shares are up about 27% in 2025 after soaring 172% last year.
Meta CEO Mark Zuckerberg holds a smartphone as he makes a keynote speech at the Meta Connect annual event at the company’s headquarters in Menlo Park, California, on Sept. 25, 2024.
Manuel Orbegozo | Reuters
Meta’s head of artificial intelligence research announced Tuesday that she will be leaving the company.
Joelle Pineau, the company’s vice president of AI research, announced her departure in a LinkedIn post, saying her last day at the social media company will be May 30.
Her departure comes at a challenging time for Meta. CEO Mark Zuckerberg has made AI a top priority, investing billions of dollars in an effort to become the market leader ahead of rivals like OpenAI and Google.
Zuckerberg has said that it is his goal for Meta to build an AI assistant with more than 1 billion users and artificial general intelligence, which is a term used to describe computers that can think and take actions comparable to humans.
“As the world undergoes significant change, as the race for AI accelerates, and as Meta prepares for its next chapter, it is time to create space for others to pursue the work,” Pineau wrote. “I will be cheering from the sidelines, knowing that you have all the ingredients needed to build the best AI systems in the world, and to responsibly bring them into the lives of billions of people.”
Vice President of AI Research and Head of FAIR at Meta Joelle Pineau attends a technology demonstration at the META research laboratory in Paris on February 7, 2025.
Stephane De Sakutin | AFP | Getty Images
Pineau was one of Meta’s top AI researchers and led the company’s fundamental AI research unit, or FAIR, since 2023. There, she oversaw the company’s cutting-edge computer science-related studies, some of which are eventually incorporated into the company’s core apps.
She joined the company in 2017 to lead Meta’s Montreal AI research lab. Pineau is also a computer science professor at McGill University, where she is a co-director of its reasoning and learning lab.
Some of the projects Pineau helped oversee include Meta’s open-source Llama family of AI models and other technologies like the PyTorch software for AI developers.
Pineau’s departure announcement comes a few weeks ahead of Meta’s LlamaCon AI conference on April 29. There, the company is expected to detail its latest version of Llama. Meta Chief Product Officer Chris Cox, to whom Pineau reported to, said in March that Llama 4 will help power AI agents, the latest craze in generative AI. The company is also expected to announce a standalone app for its Meta AI chatbot, CNBC reported in February.
“We thank Joelle for her leadership of FAIR,” a Meta spokesperson said in a statement. “She’s been an important voice for Open Source and helped push breakthroughs to advance our products and the science behind them.”
Pineau did not reveal her next role but said she “will be taking some time to observe and to reflect, before jumping into a new adventure.”