Technologies

The Sun’s Temper Tantrums: What You Should Know About Solar Storms

Solar storms are associated with the lovely aurora borealis, but they can have negative impacts, too.

Last month, Earth was treated to a massive aurora borealis that reached as far south as Texas. The event was attributed to a solar storm that lasted nearly a full day and will likely contend for the strongest of 2026. Such solar storms are usually fun for people on Earth, as we are protected from solar radiation by our planet’s atmosphere, so we can just enjoy the gorgeous greens and pretty purples in the night sky.

But solar storms are a lot more than just the aurora borealis we see, and sometimes they can cause real damage. There are several examples of this in recorded history, with the earliest being the Carrington Event, a solar storm that took place on Sept. 1, 1859. It remains the strongest solar storm ever recorded, where the world’s telegraph machines became overloaded with energy from it, causing them to shock their operators, send ghost messages and even catch on fire.

Things have changed a lot since the mid-1800s, and while today’s technology is a lot more resistant to solar radiation than it once was, a solar storm of that magnitude could still cause a lot of damage.

What is a solar storm?

A solar storm is a catchall term that describes any disturbance in the sun that involves the violent ejection of solar material into space. This can come in the form of coronal mass ejections, where clouds of plasma are ejected from the sun, or solar flares, which are concentrated bursts of electromagnetic radiation (aka light).

A sizable percentage of solar storms don’t hit Earth, and the sun is always belching material into space, so minor solar storms are quite common. The only ones humans tend to talk about are the bigger ones that do hit the Earth. When this happens, it causes geomagnetic storms, where solar material interacts with the Earth’s magnetic fields, and the excitations can cause issues in everything from the power grid to satellite functionality. It’s not unusual to hear “solar storm” and “geomagnetic storm” used interchangeably, since solar storms cause geomagnetic storms.

Solar storms ebb and flow on an 11-year cycle known as the solar cycle. NASA scientists announced that the sun was at the peak of its most recent 11-year cycle in 2024, and, as such, solar storms have been more frequent. The sun will metaphorically chill out over time, and fewer solar storms will happen until the cycle repeats.

This cycle has been stable for hundreds of millions of years and was first observed in the 18th century by astronomer Christian Horrebow.

How strong can a solar storm get?

The Carrington Event is a standout example of just how strong a solar storm can be, and such events are exceedingly rare. A rating system didn’t exist back then, but it would have certainly maxed out on every chart that science has today.

We currently gauge solar storm strength on four different scales.

The first rating that a solar storm gets is for the material belched out of the sun. Solar flares are graded using the Solar Flare Classification System, a logarithmic intensity scale that starts with B-class at the lowest end, and then increases to C, M and finally X-class at the strongest. According to NASA, the scale goes up indefinitely and tends to get finicky at higher levels. The strongest solar flare measured was in 2003, and it overloaded the sensors at X17 and was eventually estimated to be an X45-class flare.

CMEs don’t have a named measuring system, but are monitored by satellites and measured based on the impact they have on the Earth’s geomagnetic field.

Once the material hits Earth, NOAA uses three other scales to determine how strong the storm was and which systems it may impact. They include:

Geomagnetic storm (G1-G5): This scale measures how much of an impact the solar material is having on Earth’s geomagnetic field. Stronger storms can impact the power grid, electronics and voltage systems.
Solar radiation storm (S1-S5): This measures the amount of solar radiation present, with stronger storms increasing exposure to astronauts in space and to people in high-flying aircraft. It also describes the storm’s impact on satellite functionality and radio communications.
Radio blackouts (R1-R5): Less commonly used but still very important. A higher R-rating means a greater impact on GPS satellites and high-frequency radios, with the worst case being communication and navigation blackouts.

Solar storms also cause auroras by exciting the molecules in Earth’s atmosphere, which then light up as they “calm down,” per NASA. The strength and reach of the aurora generally correlate with the strength of the storm. G1 storms rarely cause an aurora to reach further south than Canada, while a G5 storm may be visible as far south as Texas and Florida. The next time you see a forecast calling for a big aurora, you can assume a big solar storm is on the way.

How dangerous is a solar storm?

The overwhelming majority of solar storms are harmless. Science has protections against the effects of solar storms that it did not have back when telegraphs were catching on fire, and most solar storms are small and don’t pose any threat to people on the surface since the Earth’s magnetic field protects us from the worst of it.

That isn’t to say that they pose no threats. Humans may be exposed to ionizing radiation (the bad kind of radiation) if flying at high altitudes, which includes astronauts in space. NOAA says that this can happen with an S2 or higher storm, although location is really important here. Flights that go over the polar caps during solar storms are far more susceptible than your standard trip from Chicago to Houston, and airliners have a whole host of rules to monitor space weather, reroute flights and monitor long-term radiation exposure for flight crews to minimize potential cancer risks.

Larger solar storms can knock quite a few systems out of whack. NASA says that powerful storms can impact satellites, cause radio blackouts, shut down communications, disrupt GPS and cause damaging power fluctuations in the power grid. That means everything from high-frequency radio to cellphone reception could be affected, depending on the severity.

A good example of this is the Halloween solar storms of 2003. A series of powerful solar flares hit Earth on Oct. 28-31, causing a solar storm so massive that loads of things went wrong. Most notably, airplane pilots had to change course and lower their altitudes due to the radiation wreaking havoc on their instruments, and roughly half of the world’s satellites were entirely lost for a few days.

A paper titled Flying Through Uncertainty was published about the Halloween storms and the troubles they caused. Researchers note that 59% of all satellites orbiting Earth at the time suffered some sort of malfunction, like random thrusters going offline and some shutting down entirely. Over half of the Earth’s satellites were lost for days, requiring around-the-clock work from NASA and other space agencies to get everything back online and located.

Earth hasn’t experienced a solar storm on the level of the Carrington Event since it occurred in 1859, so the maximum damage it could cause in modern times is unknown. The European Space Agency has run simulations, and spoiler alert, the results weren’t promising. A solar storm of that caliber has a high chance of causing damage to almost every satellite in orbit, which would cause a lot of problems here on Earth as well. There were also significant risks of electrical blackouts and damage. It would make one heck of an aurora, but you might have to wait to post it on social media until things came back online.

Do we have anything to worry about?

We’ve mentioned two massive solar storms with the Halloween storms and the Carrington Event. Such large storms tend to occur very infrequently. In fact, those two storms took place nearly 150 years apart. Those aren’t the strongest storms yet, though. The very worst that Earth has ever seen were what are known as Miyake events.

Miyake events are times throughout history when massive solar storms were thought to have occurred. These are measured by massive spikes in carbon-14 that were preserved in tree rings. Miyake events are few and far between, but science believes at least 15 such events have occurred over the past 15,000 years. That includes one in 12350 BCE, which may have been twice as large as any other known Miyake event.

They currently hold the title of the largest solar storms that we know of, and are thought to be caused by superflares and extreme solar events. If one of these happened today, especially one as large as the one in 12350 BCE, it would likely cause widespread, catastrophic damage and potentially threaten human life.

Those only appear to happen about once every several hundred to a couple thousand years, so it’s exceedingly unlikely that one is coming anytime soon. But solar storms on the level of the Halloween storms and the Carrington Event have happened in modern history, and humans have managed to survive them, so for the time being, there isn’t too much to worry about.

Technologies

U.S. diesel price tops $6 per gallon, a record high as Ukraine and Iran wars ripple through economy

U.S. diesel prices hit their highest level ever as fuel supply disruption stemming from the Ukraine and Iran wars lifts transportation costs.

U.S. diesel prices hit $6 per gallon on Friday for the first time ever, as fuel supply disruptions triggered by the Ukraine and Iran wars raises transportation costs across the entire economy.

Truckers and farmers are paying about 63% more to fill up their semis and tractors than they did at this time last year, according to data from AAA. The average price nationwide is now about $6.06 per gallon.

Prices are even higher in California, the biggest agriculture state in the U.S., at $7.98 per gallon.

Fuel costs are rising as crude oil prices have surged in response to a sharp escalation in fighting between the U.S. and Iran this month. U.S. crude oil futures topped $100 per barrel on Thursday for the first time since May. The contract has gained about 20% in September.

Diesel is the real lifeblood of the economy even though consumers tend to pay more attention to retail gasoline prices, said Bob McNally, president of Rapidan Energy, in an interview with CNBC’s “The Exchange” on Tuesday.

Higher diesel prices are passed down to consumers in what they pay for food, consumer goods and energy. Diesel fuels the trucks, trains and ships that bring goods to market. It powers the machinery that farmers use to plant and harvest food. And it heats homes and generates electricity in some cases.

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“It’s the more insidious, more costly, and more impactful fuel,” McNally said. “As we climb higher, it is a real concern.”

Diesel prices at these levels will be a “silent killer” for the economy, said Patrick De Haan, head of petroleum analysis at GasBuddy, in an interview with CNBC’s “Power Lunch” Tuesday.

Gasoline prices, meanwhile, have never been this high this late in the year, De Haan said. Prices at the pump hit a Labor Day record of $4.15 per gallon earlier this week. Americans are spending about $700 million more per day on gas and diesel than they did a year ago, the analyst said.

“There’s sticker shock there for consumers,” De Haan said.

Fuel costs are rising as the Iran and Ukraine wars have disrupted global supplies. Kyiv has pounded Russian refineries, forcing Moscow to ban diesel exports. Iran and its militant Houthi allies in Yemen have also hit the refineries of U.S. Gulf allies. Fuel exports through the Strait of Hormuz are constrained due to the Iranian attacks on tankers.

The wars in Eastern Europe and the Middle East have shut down refineries with about 5 million barrels per day of capacity, said Valero Chief Operating Officer Gary Simmons on the U.S. refiner’s July 30 earnings call.

The world has lost nearly 8% of its diesel supply with little spare refining capacity available to make up the shortfall, said Andy Lipow, president of Lipow Oil Associates, in a Wednesday note.

Rising diesel prices pose an “enormous challenge” for the Trump administration, said Helima Croft, head of global commodity strategy at RBC Capital Markets, in a Sept. 4 interview with CNBC’s “Power Lunch.”

“U.S. refineries are running at 98% utilization rates — there is just no spare capacity,” Croft said.

Technologies

Buffett’s confidence in troubled decade-old acquisition finally pays off

Warren Buffett has said he paid too much for Precision Castparts in 2016. Now its complex metal castings are in high demand.

(This is the Warren Buffett Watch newsletter, news and analysis on all things Warren Buffett and Berkshire Hathaway. You can sign up here to receive it every Friday evening in your inbox.)

Buffett’s confidence in troubled decade-old acquisition finally pays off

Six years ago, when Berkshire Hathaway took an $11 billion write-down of its $37.2 billion 2016 acquisition of Precision Castparts, Warren Buffett wrote in his annual letter to shareholders he had paid “too much” for the company, which makes “complex metal components and products.”

While it was a “fine company – the best in its business,” he had been “simply too optimistic” about its profit potential, a “miscalculation … laid bare” by the enormous downturn for the aerospace industry, Precision Castparts’ largest customers, amid the Covid pandemic.

In a CNBC interview when the deal was first announced, Buffett admitted it was “a very high multiple for us to pay,” but told shareholders at the 2016 meeting he had great confidence in Mark Donegan, the company’s CEO, both then and now, and the company’s long-term profit outlook.

It’s taken longer than he planned, but Buffett’s purchase is now looking pretty good.

As Reuters puts it, there is currently a shortage of the “complex” products Precision Castparts makes that are essential for engine turbine blades.

They’re also used in natural gas turbines, which are in demand to produce energy for artificial intelligence data centers.

This week, GE Aerospace announced it would pay $11.75 billion to acquire Consolidated Precision Products, one of the few companies that competes against Precision Castparts.

Barron’s calls that “pricey” at 26 times projected 2027 earnings before interest, taxes, depreciation, and amortization.

Using the same multiple, Barron’s estimates Precision Castparts is worth around $100 billion. That’s well above the potential value of $60 billion to $75 billion it cited in an article last month that said the unit “probably has become one of the more valuable divisions” of Berkshire.

It’s also nearly three times the 2016 purchase price.

In the Barron’s piece, Andrew Bary said Berkshire, and its share price, aren’t “getting much credit” for the subsidiary’s rising value, in part because CEO Greg Abel, like Buffett, doesn’t do analyst conference calls or investor events that could draw attention to the unit’s performance.

His recommendation: “Without Warren Buffett at the helm, Berkshire may have to start telling its story if it wants to attract a new generation of investors. This year’s trading action suggests that something may need to change.”

Berkshire bounces a bit as Wall Street sells off

Berkshire Hathaway shares managed a modest gain this week even as Wall Street’s major averages declined, a small departure from the 2026 “trading action” Bary cites.

Both the Class A and Class B shares gained almost 0.9% while the S&P 500 fell by 0.8%.

Until Friday’s bounce, that benchmark index, along with the Dow Industrials and the Nasdaq Composite, had dropped four days in a row as oil and bond yields moved higher.

Even with this week’s outperformance, Berkshire’s B shares still trail the S&P 500 by more than 10 percentage points so far this year.

Nebraska candidate moves to replace ad that included Buffett’s image

The campaign team for the Republican running in Nebraska’s 2nd Congressional District accelerated the deployment of a new campaign ad after Susie Buffett complained about a previous commercial that briefly included an image of her father, Warren Buffett.

In the ad, a picture of Buffett and his name appear on screen for roughly two seconds as candidate Brinker Harding says, “Here in Omaha, we know a thing or two about the stock market, some more than others. But we do it without insider information.”

He then goes on to highlight his call for a ban on Congressional stock trading, saying some lawmakers “trade on secrets you’ll never know,” as they “get rich” while “we barely get by.”

In a report that led its 10 PM CT newscast Wednesday evening, ABC affiliate KETV in Omaha reported Susie Buffett had asked Harding on Sept. 2 to remove the ad.

She told the station, “I think it’s worth it to say that Warren did not give Brinker his permission to use his face or name in his ad.

“It implies that my dad endorses him. He did not have permission to use it.”

The KETV report quoted Harding as saying in a statement, “In Nebraska, we work hard and support each other, and we do it honestly. Warren Buffett exemplifies that, and that was the point of my ad.”

The report said Harding did not comment on whether the ad would be taken down but noted “it does look like new ads from his campaign are beginning to run on some stations.”

A Harding campaign spokesperson told me the campaign did not think its ad implied a Buffett endorsement, but to be respectful to the Buffett family, it responded to her concern by accelerating the rollout of its next planned ad by several days, although its effort was hampered by the Labor Day weekend.

The commercial now running does not show or mention Buffett.

BUFFETT & BERKSHIRE AROUND THE INTERNET

Some links may require a subscription:

– Best’s News and Research Service: 2026 Best’s Rankings: Berkshire Hathaway Takes DPW Top Spot Among Accident & Health Lines

– Financial Times: The day Warren Buffett saved Salomon Brothers

HIGHLIGHTS FROM CNBC’S BUFFETT ARCHIVE

The effects of 9/11 on Berkshire and the insurance industry (2002)

Warren Buffett shares his thoughts on the 9/11 attacks and explains how Berkshire’s insurance companies have started taking terrorism into account when writing policies.

AUDIENCE MEMBER: I know you lost a lot of money as a result of 9/11. But I would like to know how 9/11 changed your life and your investment strategy?

WARREN BUFFETT: It made everybody, I think, in the country aware, I mean, we’ve gone through world wars and all of that, and essentially felt quite protected within these borders.

And I have been quite worried about — Charlie can attest to — you know, the possibility, particularly of some kind of nuclear device in this country, by — probably more likely by terrorists than by some, at least, declared act of war by another state.

And 9/11 made everybody realize that as humans have not progressed, particularly, in terms of how they behave with each other over the years, they have progressed enormously in their ability to inflict damage on those they hate for one reason or another…

In terms of the business aspects of it, in your question, obviously the area at Berkshire that it effects most significantly, by miles, is insurance.

And prior to 9/11, even though we recognized that there could be huge monetary damages that flowed from the activities of what I would call deranged people, we hadn’t really written the contracts in such a way as to either get paid for taking that risk or to exclude the risk. In other words, we were throwing it in for nothing.

We had excluded risk for war. I mean, we knew that we’d seen what had happened in England in the 40s, and so we had taken account of something that some of us had seen with our own eyes, but we didn’t take account of something that we knew was possible, but we just hadn’t seen. And that’s, you know, that’s the human condition, to some degree.

Since September 11th, everybody in the insurance business recognizes that they had exposures that they weren’t charging for, and they either had to exclude those exposures or they had to charge for them.

We have written — first thing we had to do, of course, is we had lots of policies on the books that left us exposed to this, and most of those policies ran for a year, starting at different points. Those have run off to a great degree, but they’re not entirely run off.

The other thing we did was on new policies. We have sold a fair amount, quite a large amount, of terrorism insurance that excludes what we call NCB, nuclear, chemical, and biological, as well as fire following nuclear.

And, we can take a fair amount of exposure to that sort of terrorism, because it doesn’t — it won’t aggregate. It aggregated at the Twin Towers in a way that — World Trade Center — in a way that just about was as extreme as you could get for non-NCB-type activities.

I mean, that was a huge amount of damage done without nuclear, chemical, or biological.

But we can have tens of billions of dollars with NCB excluded throughout a greater New York area, or something, but we can’t have hundreds of billions of exposure that would be exposed, say, to, nuclear activities, because there an act or two, or three, coordinated, could cause damage that would destroy the insurance industry.

And if we had coverage on that, it would destroy us as well.

BERKSHIRE STOCK WATCH

Four weeks

Twelve months

BRK.A stock price: $766,000.00

BRK.B stock price: $510.37

BRK.B P/E (TTM): 12.83

Berkshire Cash as of June 30: $365.5 billion (Down 8.0% from March 31)

Excluding Rail Cash and Subtracting T-Bills Payable: $359.2 billion (Down 3.8% from March 31)

Berkshire repurchased $4.5 billion of its shares in Q2 2026.

BERKSHIRE’S TOP EQUITY HOLDINGS – Sep. 11, 2026

Berkshire’s top holdings of disclosed publicly traded stocks in the U.S. and Japan, by market value, based on the latest closing prices.

Holdings are as of June 30, 2026, as reported in Berkshire Hathaway’s 13F filing on August 14, 2026, except for:

– Mitsubishi, which is as of April 30, 2026

The full list of holdings and current market values is available from CNBC.com’s Berkshire Hathaway Portfolio Tracker.

QUESTIONS OR COMMENTS

Please send any questions or comments about the newsletter to me at alex.crippen@cnbc.com. (Sorry, but we don’t forward questions or comments to Buffett himself.)

If you aren’t already subscribed to this newsletter, you can sign up here.

Also, Buffett’s annual letters to shareholders are highly recommended reading. There are collected here on Berkshire’s website.

— Alex Crippen, Editor, Warren Buffett Watch

Technologies

Wall Street firm warns AI stock rally may be nearing its end: key reasons

Capital Economics says that while the S&P 500 may keep rising this year, the AI‑driven rally shows multiple bubble indicators and is expected to peak within months, with a projected decline to 6,500 by late 2027.

Various signs of a market bubble indicate that although the S&P 500’s rally can continue this year, its medium‑term outlook appears weak because the market has become overly frothy, according to Capital Economics.

James Reilly, senior market economist at Capital Economics, noted on Thursday that most indicators point to the AI equity rally being close to its end.

Since mid‑2023, Capital has been more optimistic than most about the stock market, viewing AI as a transformative technology.

The firm’s year‑end 2026 S&P 500 forecast has consistently exceeded consensus estimates.

Nevertheless, Capital maintains that the AI‑driven rally is a bubble destined to burst.

To identify a late‑stage bubble, Reilly examines eight metrics: valuations, earnings, index concentration, equity issuance, and foreign interest in U.S. stocks.

Several of these metrics are already at or near levels seen before past market peaks.

While earnings expectations appear aligned with a market top, measures such as volatility and leverage are somewhat less concerning.

Earnings are the most significant warning sign.

S&P 500 earnings growth expectations are hovering at levels only seen at the dot‑com bubble peak, and long‑term EPS forecasts have reached a record high.

Reilly argues that the tech sector’s heavy concentration of this growth means any weakness in tech earnings will heavily drag on the index.

Additional warning signals are also emerging.

Index concentration is approaching dot‑com era extremes, net equity issuance has turned positive, and foreign ownership of U.S. stocks is at a record level.

Reilly warns that another wave of IPOs and share sales could be especially significant, as past issuance booms have historically coincided with market peaks.

He adds that, based on history, the bubble’s end is likely just months away, not years.

Leverage measures are not yet alarming compared with other factors, though the analyst cautions they are moving in a concerning direction.

Volatility indicators resemble those of a mid‑stage bubble, but constituent‑level volatility is not as extreme as at the dot‑com bust’s end.

Reilly expects the S&P 500 to rise from roughly 7,650 now to about 8,250 by the end of 2026, but ultimately projects a decline to 6,500 by the end of 2027.

These projections imply an 8% gain this year and a 21% drop in 2027.

Most signs point to the AI equity rally being close to its conclusion, Capital Economics senior market economist James Reilly stated on Thursday in a note.

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