Up until the weekend, global markets had been betting on a fragile ceasefire between the U.S. and Iran turning into a longer-term peace deal.

But escalatory rhetoric, action over the Strait of Hormuz, and fresh Iranian attacks on the United Arab Emirates over the past 48 hours, have led experts to warn war could be back.

Market analysts said the latest developments could mark an inflection point in the war and a critical moment for financial markets and global energy supplies, which are dwindling as the Strait of Hormuz remains largely closed.

“It’s an incredibly delicate moment,” Ben Powell, chief investment strategist for APAC at BlackRock, told CNBC Tuesday.

“It’s very unsettling to have our first missile warnings here in Abu Dhabi for several weeks. We were all hoping that was behind us,” the UAE-based strategist said.

“Looking forward, I think there is a genuine complexity as to whether this escalation yesterday was just part of the negotiation — Iran showing that they’ve still got cards to play, perhaps signaling to the UAE that the UAE can leave the OPEC, but energy leaving the region is still dependent on the favor from Iran — or it could be a beginning of a more difficult moment,” he told CNBC’s “Access Middle East.”

Energy and other key parts of the global economy aren’t flowing, he said, adding that it now feels like we’re approaching a “critical moment” where inventories have been run down, and the delayed impact of the energy shock is starting to come into sharper focus.

Global markets were edgy Tuesday morning after the latest developments in the Middle East at the weekend, which saw the U.S. try to end a stalemate over the blockaded Strait of Hormuz by launching “Project Freedom,” essentially, a bid to “free” stranded ships in the strait and to safely escort them out of the waterway, which has been blockaded by both Iran and the U.S.

Those attempts were met with Iranian resistance, with the U.S. saying it had sunk several Iranian boats as a result of skirmishes in the channel, although Iran denied any of its boats had been sunk.

Iran later attacked oil infrastructure in the UAE with missiles and drones, seemingly resuming a strategy of lashing out against its Middle East neighbors to get them to pressure the U.S. to end the war.

Financial markets were a mixed bag on Tuesday, with bourses lower in Asia and mixed in Europe, while U.S. stock futures moved higher ahead of the forthcoming session on Wall Street.

That apparent bounceback in the U.S. comes after the major averages suffered declines on Monday and oil prices rose amid growing concerns that the conflict in the Middle East could resume with a vengeance.

Markets are likely to remain on tenterhooks as they wait to see what happens next, with geopolitical watchers now warning that a complete collapse of the already tentative U.S.-Iran ceasefire is looking increasingly likely.

“The question of the week is whether geopolitical risks will remain messy but contained, or break through to weigh on markets and corporate earnings,” Tina Fordham, founder of Fordham Global Foresight, commented in analysis Tuesday.

“Judging by the apparent resumption today of Iranian attacks on targets in the UAE itself and on ships attempting to pass through the Strait of Hormuz, I’m currently leaning toward the latter,” she warned.

Describing the apparent resumption of Iranian drone and missile attacks against the UAE as “the biggest escalation in some weeks,” she said Tehran had shown the U.S. that it still has fight left in it, peace deal or none.

“Iran is signalling that they still have the capacity to inflict pain and won’t be forced into capitulation. The U.S. increasingly faces a choice between a long war it doesn’t want to fight, or a bad, embarrassing deal,” Fordham noted in emailed comments.

The latest turn in events in the Iran war appears to have been precipitated by the U.S.’ ‘Project Freedom’ strategy, announced on Sunday, aimed at forcing a reopening of the Strait of Hormuz. The move came after the White House appeared to have grown frustrated at an impasse over a peace deal with Iran. Pakistan-mediated talks have stalled in recent weeks, and both sides are at odds over an agreement.

U.S. President Donald Trump told Fox News Monday that Iran would be “blown off the face of the earth” if it targeted U.S. ships that are protecting commercial vessels transiting the strait.

Tehran signaled overnight that it is still interested in Pakistan-mediated peace talks with the U.S. and warned that a political solution was the only way to break the deadlock over a deal.

“As talks are making progress with Pakistan’s gracious effort, the U.S. should be wary of being dragged back into quagmire by ill-wishers. So should the UAE. Project Freedom is Project Deadlock,” Iran’s Foreign Minister Abbas Araghchi commented on X overnight.

He said the latest developments in the war “make clear that there’s no military solution to a political crisis.”

Artificial intelligence chipmaker Cerebras aims to raise as much as $3.5 billion by going public on the Nasdaq.

The company is looking to sell 28 million shares, for $115 to $125 each, according to an updated prospectus it filed on Monday.

At that range, Cerebras could be worth up to $26.6 billion in the initial public offering, based on shares outstanding. In February, the company announced a venture round that gave it a $23 billion valuation, with Advanced Micro Devices among its investors.

Relatively few technology companies have gone public since central banks raised interest rates in 2022 to fight rising prices, making investors less interested in unprofitable names.

But with the ascent of generative AI products such as OpenAI‘s ChatGPT, investors have become rabid about betting on companies that benefit from the trend. Money-losing Cerebras competitor CoreWeave, which rents out Nvidia graphics processing units as a cloud service, raised $1.5 billion in an IPO last year. Cerebras’ chips are an alternative to Nvidia’s popular GPUs.

Cerebras sought to go public in 2024 but later withdrew the paperwork, as its business model was shifting away from selling hardware and toward operating a cloud service based on its own chips. In April, Cerebras filed for an IPO for a second time.

In January, Cerebras said it would provide up to 750 megawatts of AI computing power to OpenAI through 2028 in a transaction worth over $20 billion.

The company’s fourth-quarter revenue grew about 76% year over year to $510 million, and it showed $87.9 million in net income for the period.

Andrew Feldman, Cerebras’ co-founder and CEO, is not selling shares in the IPO. He will own 10.3 million shares after the IPO that would be worth up to $1.28 billion at the high end of the range, according to the filing.

The company has an option to sell an additional 4.2 million shares to underwriters after the IPO that would yield another $525 million in proceeds at the high end of the range.

WATCH: OpenAI unveils first AI model running on Cerebras chips

BALTIMORE/NEW YORK — Spirit Airlines was hours away from its final flights Friday afternoon. Jeremiah Burton was hours away from his first.

“It’s my first time flying,” Burton, a 45-year-old air conditioning and heating technician, told CNBC at Baltimore/Washington International Thurgood Marshall Airport on Friday, shortly before he was scheduled to depart for New Orleans to visit his daughter and her newborn twins.

“To tell you the truth, I just went online and Googled the cheapest airline ticket,” he said, adding that he paid about $500 for the trip late last month. He was scheduled to return on May 6.

While Burton waited for his flight, Spirit was making final preparations to shut down overnight, ending a three-decade run that brought discount air travel to millions across the United States and as far away as Peru. Spirit canceled international flights on Thursday, to start, so travelers, planes, and flight crews wouldn’t be stranded. The airline said it flew more than 50,000 people the day leading up to its collapse.

Spirit bondholders rejected an 11th-hour bailout proposal from the Trump administration that could have included up to $500 million to keep the ailing airline afloat. The deal would have put the government ahead of other bondholders’ claims and given it an up to 90% stake in the airline.

Commerce Secretary Howard Lutnick called Spirit CEO Dave Davis to tell him there was no deal and that bondholders and the government were far from an agreement, according to a person familiar with the matter. Bondholders sent a letter to Spirit’s board, confirming that the end was near.

Before dawn on Saturday, Spirit’s website and app were papered over with the message that operations had ended. “To our Guests: all flights have been cancelled, and customer service is no longer available,” it read.

By noon, LaGuardia’s Marine Air Terminal, an Art Deco facility that opened in 1940 and was home to Pan Am’s Clippers — and, most recently, home to Spirit at the New York airport — was nearly silent.

Cibo Express closed half a day early with no customers to serve. CNBC saw the last Transportation Security Administration officer who was sent home early. Screens on the arc of yellow kiosks read: “We regret to inform you that Spirit Airlines has ceased global operations.”

“It has been an honor to bring friends and families closer together for 34 years,” it said at the bottom, with a QR code with next steps.

United Airlines, Frontier Airlines, American Airlines, Southwest Airlines, JetBlue Airways and others said they are capping fares to get travelers home. United said about 14,000 Spirit customers booked tickets on United on Saturday. JetBlue also announced plans to expand its schedule at Fort Lauderdale with a host of new services to destinations ranging from Cali, Colombia, to Nashville, Tennessee.

Crews scrambled to get home.

Jon Jackson, a Spirit Airlines captain, was supposed to fly his retirement flight on Saturday, but his airline shut down before he could.

He hopped on a Southwest flight to get back to Baltimore from Fort Lauderdale. While on board, “we casually mentioned it to the crew,” his son, Chris, a Southwest pilot, said in a Facebook post. Southwest staff organized a water cannon salute when the aircraft arrived and he was met with applause and a reception when he walked off the jet bridge, according to the post, which was confirmed to CNBC by Southwest.

While things came to a head this week with access to cash drying up, Spirit’s problems were years in the making. It was profitable in the 2010s and expanded rapidly as customers filled planes. But it last made money in 2019.

The carrier has faced intense competition from richer, giant rivals like Delta Air Lines, United Airlines and American Airlines.

Spirit was also under pressure from rivals’ own bare-bones fares, soaring costs, a failed acquisition by JetBlue Airways that the Biden Justice Department successfully challenged, and an engine defect that grounded many of its jets. Airlines grew more reliant on high-spending customers who shell out thousands for plush, premium cabins. Most recently, the surge in jet fuel prices resulting from the war in Iran was a challenge the airline couldn’t overcome, it said.

Last August, Spirit filed for bankruptcy protection for the second time in less than a year, and analysts said part of the reason was that it hadn’t done enough to reconfigure the airline, slash costs, and that it had avoided hard decisions in its first filing in 2024. Weeks before it had hoped to emerge free from its bankruptcy, it faced the added challenge of expensive fuel.

Some 17,000 direct and indirect employees lost their jobs as a result of the airline’s collapse, the carrier said.

“The pain of this decision will not be felt in boardrooms. It will be felt by pilots, flight attendants, mechanics, dispatchers, and ground crews, and by the families and communities that depend on them,” wrote Air Line Pilots Association’s international president, Jason Ambrosi, on Saturday.

Sara Nelson, president of the Association of Flight Attendants-CWA, Spirit’s roughly 5,000 flight attendants’ union, wrote a letter to Transportation Secretary Sean Duffy and acting Labor Secretary Keith Sonderling, urging them to try to help ensure that flight attendants are paid and compensated for earned vacation and per diems as the case works its way through bankruptcy court. She also asked that they receive a $600 weekly supplement to state unemployment from the federal government.

“Standard unemployment coverage does not replace full wages, and this enhanced support would help stabilize households while workers secure new employment,” she said.

Spirit had just about 4% of the U.S. market share, according to aviation-data firm Cirium, but an outsized presence in many Americans’ minds — and on their social media feeds.

Henry Harteveldt, Atmosphere Research Group founder and former airline executive, said Spirit was a “true pioneer” of discount air travel but still was the “airline America loved to hate,” in part because of its bare-bones fares, customer service debacles, and spotty reliability in earlier years.

Spirit became a favorite punchline among comedians. “The CEO of Spirit Airlines was like, ‘With $500 million [from the Trump administration] our planes could have two wings again,” “Tonight Show” host Jimmy Fallon said last month.

In 2017, Spirit enrolled customer-facing employees in the Disney Institute, a Disney leadership and professional training subsidiary, to improve its staff interactions with customers and had made strides in improving its on-time performance.

It still had fans and willing customers, right up until the end.

“For a two-hour flight, I could really suffer a lot,” said Kara Snyder, 30, who works in health insurance sales. She said that for a short flight from Florida to Baltimore, scarce legroom and perks don’t matter to her. Snyder said she flew Spirit to Baltimore and was flying back to Orlando on Frontier Airlines. “I tend to stick with budget airlines,” she said.

International flights to Europe or Africa are another matter, said Snyder. “I go Delta,” she said. “I’m picky on that. It has to be Delta.”

Friday evening at Spirit’s headquarters in Dania Beach, Florida, near its home base of Fort Lauderdale-Hollywood International Airport, Spirit’s executive team was huddled in a war room, watching its last flights come in.

News broke earlier that at 3 a.m. on Saturday, the clock would run out for the airline and its fleet of bright yellow jets.

“Good luck to you all,” said an American Airlines employee to a Spirit flight, according to audio posted by LiveATC.net. “Sorry to hear what happened.”

One of the pilots on the last Spirit flight, NK1833 from Detroit to Dallas Fort Worth International, shortly before touching down after midnight Saturday, asked the tower: “Is there any other Spirit flights coming in after us?” There were 175 passengers on board.

“I don’t see anything,” the controller said. “So you might be the last one.”

He later told the pilot, “Well, it was a pleasure working with you guys and I wish you the best.”

“Thank you very much,” the pilot replied, according to LiveATC.

Wes Egan, a Spirit dispatcher for roughly 23 years, told CNBC that he was working in the company’s operations center in Orlando late Friday when one of the carrier’s pilots was asking for information about the fate of the airline. Senior managers had just informed the staff there around 11:30 p.m. that operations were about to cease.

He sent a text message to the pilot via a special cockpit system for alerts and other information.

“UNOFFICIALLY WE STOP FLYING AT 0300 EST ON 05/02,” said the message. “GODSPEED MY FRIEND.”