The world’s ten most valuable companies were worth $28.14 trillion at the close on Friday, 30 October, down $1.52 trillion from $29.66 trillion at the end of September, by our arithmetic. Alphabet, Google’s parent, lost $780.2 billion, about 51% of the ten’s combined fall.
The same ten companies held the top ten places on both dates, and all but Amazon and TSMC changed rank. Apple, which passed Nvidia on Friday at $5.03 trillion according to AppleInsider, finished first, and Nvidia second.
Business Pill · Power Law
A short Business Engineer explainer on power laws, where a few outcomes account for most of the value. It teaches the general idea only and does not discuss the companies in this story.
The key insight: By our arithmetic, the world’s ten most valuable companies lost $1.52 trillion of market value in October, and Alphabet’s $780.2 billion fall was about 51% of it.
By our arithmetic, the top five at the 30 October close were Apple at $5.03 trillion, Nvidia at $4.93 trillion, Microsoft at $3.88 trillion, Alphabet at $3.43 trillion and Amazon at $2.60 trillion. Next came TSMC at $1.89 trillion, Saudi Aramco at $1.67 trillion, Tesla at $1.58 trillion, Meta at $1.57 trillion and Broadcom at $1.56 trillion.
At the end of September the order was Nvidia, Apple, Alphabet, Microsoft, Amazon, TSMC, Meta, Broadcom, Saudi Aramco and Tesla. Apple and Nvidia swapped first and second. Microsoft moved up to third, Aramco to seventh and Tesla to eighth, while Alphabet slipped to fourth, Meta to ninth and Broadcom to tenth.
The ten most valuable companies, market value on 30 September 2026 (open circle) and 30 October 2026 (filled), ranked by their 30 October value. Market values are our arithmetic from Yahoo Finance closing prices and SEC filing cover share counts (Saudi Aramco: Yahoo Finance share count and its 29 October close). FourWeekMBA.
Four Rose, Six Fell
Tesla added $177.9 billion in October, Apple $169.4 billion, Microsoft $66.9 billion and Aramco $45.2 billion, a combined $459.4 billion, by our arithmetic. The six that fell lost a combined $1.98 trillion.
After Alphabet, the largest falls were Nvidia at $572.1 billion, Meta at $281.7 billion, TSMC at $130.9 billion, Broadcom at $119.9 billion and Amazon at $95.2 billion. In percentage terms, Alphabet fell 18.5%, Meta 15.2% and Nvidia 10.4%.
Reuters reported that the broader chips index ended October with a monthly loss of more than 15%, as we noted in our Friday piece. Alphabet’s first-session drop after its results, which we counted separately, accounts for most of its monthly loss.
The Business Lever: Concentration at the Top
As we read the figures, October moved value between the largest companies rather than out of the group’s membership: no company entered or left the ten. Just below them, Eli Lilly closed at $1.33 trillion after adding $245.0 billion in the month, by our arithmetic.
Market values here are our arithmetic: each company’s closing price, from Yahoo Finance, multiplied by the shares outstanding on the cover of its latest SEC filing, with the same share count used for both dates. Saudi Aramco, Samsung Electronics and SK Hynix use Yahoo Finance share counts, and prices outside the US are converted at the day’s exchange rate.
The Structural Read
As we read the figures, the ten stayed the same ten, so October moved value among the largest companies rather than replacing any of them.
As we read the split, the four that rose added $459.4 billion between them, against $1.98 trillion lost by the six that fell, by our arithmetic.
AppleInsider
“has been going back and forth between Apple and Nvidia for some time now, as iPhone and Services demand go up against AI chip consumption”
Three Implications
FOR INDEX WEIGHTSApple ended October first at $5.03 trillion, AppleInsider reported, with Nvidia second at $4.93 trillion.
FOR ALPHABET Its $780.2 billion fall took it from third to fourth, behind Microsoft, by our arithmetic.
FOR THE NEXT TIER Eli Lilly closed at $1.33 trillion after adding $245.0 billion in October, by our arithmetic.
The framework says the AI Supercycle has “a dual character that is simultaneously a bubble and a supercycle”.
As we read it, October’s $1.52 trillion fall among the ten largest companies, with no change in which ten they were, is one month of that dual character showing up in market values. The framework predates these figures and does not discuss them.
These are closing-price snapshots on two dates, not a measure of returns including dividends. Share counts are taken from each company’s latest filing and are not adjusted for buybacks or issuance during October. Aramco’s figure uses its 29 October close, its last October session.
This Week In The AI Supercycle
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This week’s issue: for two years the AI build-out was priced as a growthstory. This week it started being priced as a credit story.
The ten most valuable companies lost about $1.52 trillion of market value in October, by our arithmetic, with Alphabet’s $780.2 billion fall the largest single part and Apple ending the month first.
A note on sourcing. Market values are our arithmetic: Yahoo Finance closing prices multiplied by shares outstanding from each company’s SEC filing cover (Yahoo Finance share counts for Saudi Aramco, Samsung Electronics and SK Hynix), converted to US dollars at the day’s exchange rate where needed. They are snapshots, not total returns, and not investment advice.
Gennaro Cuofano is a CRO and tech executive who has worked in AI since late 2015, starting with bringing NLP, natural-language generation, voice and chatbot products to the marketing industry. His background is in law and finance: he holds a Master's degree in Law and an International MBA with an emphasis on corporate finance (LUISS Business School and the University of San Diego, 2012), and worked as a financial analyst at a real-estate investment firm in San Diego and as an assistant controller. His work focuses on business model strategy, business engineering and, more broadly, structural analysis: how companies make money, read from their own filings. He created FourWeekMBA and leads research there and at The Business Engineer, his newsletter on AI and business strategy, with over 95,000 subscribers and more than 1,000 published analyses. His writing has also appeared on Entrepreneur (for example, How to Digitize a Family Business in Europe) and HackerNoon. Find him on LinkedIn and Substack. See how we source.
