Microsoft once wrote off $7.6 billion on a phone business. It also once launched a chatbot that lasted about 16 hours. Both count as failures, but they aren't remotely the same size, and most "biggest fails" lists treat them like they are.
Microsoft can afford to fall on its face. In fiscal 2026 it brought in about $332 billion in revenue, and Azure alone passed $100 billion for the first time. That means its flops tend to be big, expensive, and well documented, which makes them fun to pick apart.
I ranked these by damage: money lost, ground handed to rivals, and how long the mess hung around. Where Microsoft put a dollar figure on something, I used it. Vista never got a tidy price tag, and Windows 8 only sort of did, so the middle of the list is my call. I'll say why on the close ones. One thing worth knowing about the numbers: a write-down is a non-cash charge. The money was spent years earlier, and the write-down is the moment the company admits it isn't coming back.
Here we go, smallest hit to biggest.
5. The Xbox 360's Red Ring of Death (2005-2007)
The Xbox 360 came out in November 2005, and by the end of June 2007 it had sold 11.6 million units. That's a solid number, though a bit under the 12 million Microsoft had predicted. The trouble was a hardware failure that showed up as three flashing red lights on the front of the console. Gamers called it the Red Ring of Death.
In July 2007, Microsoft stretched the warranty for that error to three years, up from one in the U.S. and two in Europe, and promised refunds to people who had already paid for repairs. It also announced a charge of up to $1.15 billion. Robbie Bach, who ran the entertainment division, admitted repairs were happening at a rate the company didn't like. What Microsoft wouldn't say was what exactly was breaking.
It's only #5 because it was a fixable defect in a console people kept buying. Microsoft paid up, and the console went on to sell well.
4. Windows 8 and Surface RT (2012-2013)
Windows 8 launched in October 2012 as Microsoft's attempt at one operating system for tablets and PCs. It pushed a touch-first design onto a lot of people who weren't using touchscreens. The Start button and Start menu vanished, and a full-screen wall of tiles took over. It felt like the OS had been designed for somebody else.
The backlash got loud enough that Steve Ballmer admitted Microsoft had pushed too boldly. Windows 8.1 arrived in October 2013 with a Start button and an option to boot straight to the desktop. But that button only took you to the tile screen. The real Start menu didn't come back until Windows 10 launched on July 29, 2015.
The tablet side went even worse. In July 2013, Microsoft cut the price of its ARM-based Surface RT by $150, down to $349, and took a $900 million charge for inventory adjustments.
Why is this above the Red Ring, when the Red Ring's charge was bigger ($1.15 billion versus $900 million)? Because the Red Ring was a fixable defect in a product people wanted. Windows 8 was a strategic misjudgment about Microsoft's flagship product, and it took nearly three years, from that October 2012 launch to Windows 10, to fully undo. The lesson, if there is one: don't take away the thing people click on every day.
3. Windows Vista (2007)
Following Windows XP was never going to be easy, and Vista made it harder by showing up late with a reputation as a resource hog. Then came the "Windows Vista Capable" stickers. Microsoft let PC makers put them on machines that could only run the most basic edition of Vista, the one without the flashy features in the ads. A lawsuit followed. It was certified as a class action, and the judge later reversed that.
Vista's security pop-ups became a running joke. Apple made an ad out of them, with a bodyguard standing behind the "PC" character asking "cancel or allow?" over and over. Businesses weren't laughing either. Surveys around 2008 and 2009 found roughly half of corporate IT buyers planned to skip Vista and wait for Windows 7.
That's the real damage. Vista turned a delay into a credibility problem, and a lot of customers simply waited it out. Early Windows 7 testers, for what it's worth, rated it far higher than Vista's beta testers had rated Vista.
2. The aQuantive Deal (2007-2012)
You probably forgot this one, and honestly so did investors. In 2007, Microsoft paid just over $6.3 billion in cash for aQuantive, an online advertising company, partly to counter Google's purchase of DoubleClick. At the time it was the biggest acquisition in Microsoft's history.
Five years later, in July 2012, Microsoft wrote down about $6.2 billion of its Online Services goodwill, mostly tied to the deal. The company said the acquisition hadn't accelerated growth as much as it had hoped. In plain terms, it was effectively worthless, and the charge wiped out the quarter's profit.
It's #2 even though almost nobody remembers it, because only the Nokia deal comes close as a total loss on this list. Microsoft wrote off roughly $6.2 billion of a roughly $6.3 billion price, and the reason for buying it, taking on Google in online ads, never came together. It also edges out Vista because its damage can be measured in Microsoft's own words, while Vista's costs were never tallied.
1. Windows Phone and the Nokia Acquisition (2010-2015)
Microsoft was slow to see the iPhone and Android coming, and its late response never caught up. Then it bought Nokia's phone business. It announced the deal in September 2013 and closed it in April 2014. Steve Ballmer pushed it through in his last months as CEO, over objections from several executives, Satya Nadella among them. Nadella ended up inheriting the mess.
The final price was about $7.9 billion, according to an SEC filing, though headlines at the time said roughly $7.2 billion. In July 2015, Microsoft took a $7.6 billion impairment charge and announced about 7,800 more layoffs. Add restructuring and integration costs and the fiscal 2015 hit came to nearly $10 billion.
The core problem was apps. Developers didn't want to build for a platform with few users, and users didn't want a phone without the apps. In 2017, a Microsoft corporate VP pointed to that shortage when the company stopped adding features to Windows 10 Mobile. Support ended on December 10, 2019.
Buying the hardware maker didn't fix any of that. It's the most expensive lesson on this list.
The Ones Everybody Remembers
These didn't cost billions, but they're the failures people actually bring up.
The Zune (2006): Microsoft's iPod rival launched in November 2006 in black, white, and, famously, brown. The big feature was wireless song sharing, nicknamed "squirting," but licensing limits meant a shared song only worked three times over three days. Then on December 31, 2008, 30GB Zunes froze at midnight because of a leap-year bug in a third-party clock driver. They fixed themselves about 24 hours later. Microsoft discontinued all Zune hardware in October 2011.
Tay (2016): Microsoft's Twitter chatbot, aimed at 18-to-24-year-olds, got manipulated into posting offensive content and was shut down about 16 hours after launch. Peter Lee, Microsoft's corporate vice president of research, said the team had prepared for many kinds of abuse but missed this one. Microsoft briefly switched Tay back on a few days later and pulled it again after more erratic behavior.
Microsoft Kin (2010): Microsoft pulled the plug on the Kin phone on June 30, 2010, just 48 days after it went on sale. It had reportedly taken about two years and $1 billion to build.
Xbox One's original policies (2013): When Microsoft unveiled the console in May 2013, it came with used-game restrictions and a daily online check-in. Microsoft reversed both in June, weeks later and before the console launched.
Still Playing Out: Recall and the Copilot+ PC Brand (2024-2026)
Recall drew so much backlash in 2024 that Microsoft delayed it a full year over security and privacy concerns. In early 2026, Windows Central reported, citing unnamed sources, that Microsoft was reviewing Recall and weighing scaling back Copilot features across Windows. Then in late September 2026, a Surface executive confirmed the new Surface PCs won't carry the Copilot+ PC label, even as Microsoft pushes Copilot itself harder. It's too early to rank this one.
So What Did We Learn?
Look at the top five and a pattern shows up, at least to me. The costliest failures came when Microsoft bought or muscled its way into markets it didn't really understand yet: phones, online ads, tablets. The most embarrassing ones came from shipping before things were ready, like Vista and the Red Ring.
None of it sank the company. In fiscal 2013, the year of the Surface RT charge, Microsoft still reported $26.76 billion in operating income on $77.85 billion in revenue, and by fiscal 2026 revenue had reached about $332 billion. Five expensive lessons, and Microsoft barely broke stride.
Sources
Company financials
Microsoft fiscal 2013 results: IT World Canada
Microsoft fiscal 2026 results: Redmond Magazine, SEC 8-K
5. Xbox 360
New York Times, July 6, 2007 (units sold and the sales target)
4. Windows 8 and Surface RT
3. Windows Vista
2. aQuantive
1. Windows Phone and Nokia
Small fails
Zune: Microsoft launch release, Wikipedia: Zune, Wikipedia: Zune 30
Tay: Silicon UK, The Hacker News, Vice
Xbox One: BusinessTech
Recall and Copilot+
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