孫正義 · 1957 – 2026 · Tosu → Berkeley → Tokyo → the world

Masayoshi Son and the bet

He was born beside a railway line in Kyushu, sold his first invention to Sharp at 20, and founded SoftBank at 24. He became the richest person on earth for three days, then lost more money than anyone in history. Since then he has rebuilt the fortune with bets on Alibaba, Arm and OpenAI.

drag to spin
1981SoftBank founded, aged 24
$20M→$58BAlibaba stake, 2000 to the 2014 IPO
−$70BPersonal loss in the 2000–01 dot-com crash
$500BStargate AI plan, January 2025
Masayoshi Son smiling, photographed at SoftBank headquarters in Tokyo in May 2025
Son at SoftBank's Tokyo headquarters, 12 May 2025
SoftBank's founding philosophy

"Information Revolution — Happiness for everyone."

Son has run SoftBank for 45 years on a single idea: whoever owns the infrastructure of the next information wave wins. That idea took him from software distribution to the web, to mobile phones, to chips and now to artificial intelligence. It has made him a fortune three times and nearly ruined him once.

Exhibit A · Net worth, 1999 – 2026

Forty-five years of fortune, in one line

Approximate personal net worth in US$ billions, at moments reported by Forbes and Bloomberg. Hover or tap the line for each point.

01
1957 – 1973

Tosu, Kyushu

A Zainichi Korean childhood beside the railway tracks.

Illustration: the settlement beside the tracks near Tosu station, where Son grew up.
  1. 11 August 1957

    Born in Tosu, Saga Prefecture

    Son is born into a Zainichi Korean family in Tosu, a railway junction town on Kyushu, Japan's southern main island. His grandparents had come to Japan from Korea. The family lives in an unlicensed settlement beside the railway tracks.

  2. 1960s

    Poverty, prejudice and a borrowed name

    The family raises pigs and chickens and uses the Japanese surname Yasumoto, as many Korean families then did. Son has described being hit by a stone thrown by a classmate because of his heritage. His father, Mitsunori, later builds a business running pachinko parlours and moves the family to Kitakyushu and then Fukuoka.

  3. 1973 · age 15–16

    Doorstepping Den Fujita

    Inspired by a novel about the samurai reformer Sakamoto Ryōma, Son keeps calling the office of Den Fujita, founder of McDonald's Japan, until he gets 15 minutes. Fujita tells him to study computers, and to go to America.

02
1974 – 1980

California and the first million

An invention a day, a deal with Sharp and a room full of arcade machines.

Sather Tower, the clock tower of UC Berkeley, rising above redwood trees
Sather Tower, UC Berkeley, where Son studied economics from 1977 to 1980
  1. 1974 · age 16

    Leaves school in Fukuoka for California

    He enrolls at Serramonte High School in Daly City, moves up the grades in weeks and passes the high-school equivalency exam. After Holy Names College in Oakland he transfers to UC Berkeley in 1977.

  2. 1977 · age 19

    An invention a day

    He spends a few minutes every day inventing something and fills a notebook with about 250 ideas. The one he chooses is a pocket translator that speaks: type a word in one language and hear it in another.

Exhibit B · The invention

The speaking translator

Son recruited Berkeley physicist Forrest Mozer, a pioneer of speech synthesis, and a small team to build the prototype, paying them only if it sold. In 1978 he took it to Japan.

Sharp

Sharp, then the leading maker of pocket calculators, bought the rights for about ¥100 million, roughly $1 million. It is often remembered as a calculator deal. The device was a translator, built on calculator hardware.

≈ $1M+ · his first real money
Exhibit C · Playable

The machine that paid for Berkeley

Son imported used Space Invaders cabinets from Japan and installed them in bars and cafés around campus. They reportedly earned him over $1 million. Move with ← → (or the buttons) and fire with space.

SPACE INVADERS · 1978

SCORE
0000
Coins in the box: $0
An original Space Invaders upright arcade cabinet
An original Space Invaders cabinet
  1. 1978 · age 20

    The Sharp deal closes

    Sharp's later line of electronic translators grows out of the prototype. Son is 20 and has his first million dollars.

    ≈ ¥100M licence
  2. 1979 – 1980

    Unison World, and a promise to his mother

    With classmate Hong Lu he starts a software company, Unison World. He graduates in 1980 and, keeping a promise to his mother, sells out and goes home to Japan.

03
1981 – 1994

Founding SoftBank

Two part-timers, an apple crate and a promise of trillions.

  1. 1980 – 1981

    Forty business plans

    In Fukuoka he spends about 18 months testing some 40 business ideas against questions like "will I still be passionate about this in 50 years?" He chooses personal-computer software distribution, a business that barely existed in Japan.

Exhibit D · 3 September 1981
SoftBank

Nihon SoftBank is founded with ¥10 million of capital. On his first day Son climbs onto an apple crate and tells his two part-time employees that revenue will one day be counted in trillions of yen (兆, chō). Both quit soon after. SoftBank's revenue passed ¥1 trillion in the 2000s.

  1. 1982

    Distribution deals and magazines

    A deal with retailer Joshin Denki puts SoftBank in front of buyers nationwide. It launches PC magazines including Oh! PC and Oh! MZ.

  2. 1983 – 1986

    Chronic hepatitis

    Aged 25 he is diagnosed with chronic hepatitis and given a poor prognosis. He spends much of three years in hospital, reading thousands of books, until an experimental treatment works. He returns as president in 1986.

  3. 1990

    Becomes a Japanese citizen as "Son"

    Officials expected naturalised citizens to take a Japanese surname. His Japanese wife first legally changes her own name to Son, which creates a precedent, and he naturalises under his Korean family name.

  4. July 1994

    SoftBank goes public

    The listing gives Son shares to buy with, and he starts spending them immediately.

04
1995 – 1999

Buying the internet early

Two bets that would define his fortune.

  1. 1995 – 1996

    A US buying spree

    SoftBank buys the COMDEX trade show for about $800 million, Ziff-Davis Publishing for about $2.1 billion and 80% of memory maker Kingston Technology for about $1.5 billion. Ziff-Davis points him at a small web directory run by two Stanford students.

  2. 1995 – 1996

    Yahoo

    After about $2 million in late 1995, SoftBank invests roughly $100 million in 1996 for around a third of Yahoo, just before its April IPO. Yahoo Japan, a joint venture, becomes Japan's dominant web portal.

    Yahoo!
  3. 1998

    Onto the Tokyo Stock Exchange

    SoftBank moves to the TSE's First Section while stakes in E*Trade, GeoCities, UTStarcom and hundreds of other web companies pile up.

  4. Late 1999 – January 2000

    Alibaba: the six-minute decision

    Son meets Jack Ma, a former English teacher running a trading site from a Hangzhou apartment. By most accounts he decides to invest within minutes. SoftBank puts in $20 million in January 2000.

    Alibaba
Exhibit E · Drawn to scale

$20 million became about $58 billion

$20M

The squares are drawn to scale by area. The gold speck in the corner is the original cheque. The green square is the stake's value at Alibaba's IPO in September 2014, about 2,900 times larger.

05
2000 – 2001

The largest wipeout in history

Richest person alive for three days, then the biggest loser on record.

  1. February 2000

    The peak

    SoftBank is worth about $200 billion at the top of the bubble. Son's paper fortune, about $78 billion, briefly makes him richer than Bill Gates. At times it is rising by around $10 billion a week.

    "For three days, I was the richest man in the world."Son, recalling February 2000
Exhibit F · Press to crash
Masayoshi Son, personal net worth
$78.0B
February 2000
  1. March 2000 – 2001

    The crash

    The dot-com bubble bursts. SoftBank's shares fall about 75% in two months and more than 90% by the end of 2000. Within about a year Son's fortune drops from roughly $78 billion to about $1 billion, a loss of around $70 billion. It is the largest loss of personal wealth on record. He sells almost nothing.

    ≈ −$70B personal wealth
  2. September 2001

    He doubles down: Yahoo! BB

    Instead of retrenching, SoftBank launches Yahoo! BB, a cut-price ADSL broadband service. Staff hand out free modems on street corners. It loses money for years but forces Japanese broadband prices down and gives SoftBank a telecom business.

06
2004 – 2015

The telecom rebuild

From ADSL to Japan's iPhone carrier and an American network.

  1. 2004 – 2005

    Japan Telecom, and a baseball team

    SoftBank buys fixed-line carrier Japan Telecom (2004) and Fukuoka's Daiei Hawks baseball club, renamed the SoftBank Hawks (2005).

  2. March 2006

    Buys Vodafone Japan for ¥1.75 trillion

    About $15 billion, then one of Asia's largest leveraged buyouts. It becomes SoftBank Mobile.

    VodafoneSoftBank Mobile
    ≈ $15B acquisition
  3. 11 July 2008

    The iPhone comes to Japan, through SoftBank only

    After lobbying Steve Jobs personally, Son launches the iPhone 3G in Japan as its only carrier. Subscriber numbers climb for years.

Masayoshi Son smiling in a black iPhone 3G polo shirt on launch day
Launch day, 11 July 2008
Masayoshi Son with the first customers at an iPhone 3GS launch event in Tokyo
iPhone 3GS launch, Tokyo, June 2009
Masayoshi Son on stage at the SoftBank Mobile Summit
SoftBank Mobile Summit, September 2008
  1. June 2010

    The 300-year plan

    Son presents "SoftBank's Next 30-Year Vision" and describes SoftBank as a company built to last 300 years.

  2. July 2013

    Sprint

    SoftBank completes a $21.6 billion purchase of about 78% of US carrier Sprint. Sprint struggles for years and merges into T-Mobile US in April 2020.

    Sprint
  3. 19 September 2014

    Alibaba's IPO pays out

    Alibaba lists in New York in what was then the largest IPO ever, raising $25 billion. SoftBank's stake of about 32% is worth roughly $58 billion at the offer price.

    ≈ 2,900× on $20M
Masayoshi Son waving from an open car among cheering fans at the SoftBank Hawks victory parade
Son (right, waving) at the SoftBank Hawks championship parade, Fukuoka, December 2011
07
2016 – 2022

Arm, Vision Fund and WeWork

The largest tech fund ever raised, and its worst years.

  1. 18 July 2016

    Buys Arm for £24.3 billion

    About $32 billion for the Cambridge chip designer whose designs run nearly every smartphone. It is a bet that Arm's designs will end up in every connected device.

    Arm
  2. 6 December 2016

    Trump Tower

    Son meets President-elect Trump and pledges $50 billion of US investment and 50,000 jobs.

Exhibit G · Who put up $100 billion
SoftBank Vision Fund

The fund's first close in May 2017 was $93 billion, rising to about $98.6 billion. Circle areas are to scale. "Others" includes Apple, Qualcomm, Foxconn and Sharp.

  1. 2017 – January 2019

    The Nvidia stake he sold

    SoftBank builds a 4.9% stake in Nvidia for about $4 billion and sells it in early 2019, after a chip-stock slump, for a profit of a few billion dollars.

    Nvidia
Exhibit H · What if he had held on?

4.9% of Nvidia, through time

$80BNvidia's approximate market value
$3.9BA 4.9% stake would be worth
1×versus the 2019 sale value

Market values are rounded approximations. The point is the shape: the stake he sold for a few billion would later have been worth well over $100 billion.

  1. August – September 2019

    WeWork unravels

    WeWork's IPO filing exposes its losses and governance. The listing is pulled on 30 September. SoftBank rescues it, taking total exposure past $18 billion. Son admits his "investment judgment was poor in many ways." WeWork files for bankruptcy in November 2023.

    WeWork
Exhibit I · Valuation, approximate
Jan 2019
$47B
Sep 2019 IPO talk
$15B
Oct 2019 rescue
$8B
Oct 2021 SPAC
$9B
Nov 2023
Ch. 11
  1. May 2020

    Vision Fund loses ¥1.9 trillion

    Covid and write-downs on WeWork and Uber produce an annual Vision Fund loss of about ¥1.9 trillion (≈ $18 billion). SoftBank announces a ¥4.5 trillion asset sale to buy back shares and cut debt.

  2. 13 Sep 2020 – 8 Feb 2022

    The Arm sale to Nvidia is blocked

    SoftBank agrees to sell Arm to Nvidia for $40 billion. Regulators in the US, UK and EU object, and the deal is abandoned.

  3. May & August 2022

    Record losses

    SoftBank loses ¥1.7 trillion (≈ $13 billion) for the year to March 2022, then ¥3.16 trillion (≈ $23 billion) in a single quarter. Son says he is "ashamed" and switches SoftBank into "defence mode".

    ≈ −$23B in one quarter
08
2023 – 2026

All in on AI

Arm relisted, Nvidia sold again, OpenAI bought big.

  1. 14 September 2023

    Arm relists on Nasdaq

    Arm prices at $51 a share, valuing it at about $54.5 billion. SoftBank keeps around 90%. As AI-chip demand lifts Arm's stock, the stake becomes the main source of Son's rebuilt fortune.

  2. 5 August 2024

    Tokyo's Black Monday

    On the Nikkei's worst day since 1987, SoftBank shares fall about 19%, their steepest drop since listing.

    −19% in a day
  3. October 2024

    The first OpenAI cheque

    SoftBank invests about $500 million in OpenAI's $6.6 billion funding round.

  4. 21 January 2025

    Stargate, at the White House

    With President Trump, Sam Altman and Larry Ellison, Son announces Stargate, a venture of SoftBank, OpenAI, Oracle and MGX to spend up to $500 billion on US AI data centres over four years. Son is chairman.

    OpenAI
Exhibit J · Film

"The U.S. is the center of innovation"

A White House clip of Son speaking about the Stargate project. About two minutes, with sound.

Each light above is roughly $1 billion of Stargate's planned $500 billion.

Sam Altman, Masayoshi Son and Prime Minister Shigeru Ishiba standing together in the Prime Minister's office
With Sam Altman (left) and Prime Minister Shigeru Ishiba, Tokyo, 3 February 2025
  1. 31 March 2025

    Leads OpenAI's $40 billion round

    SoftBank commits up to $30 billion of a $40 billion raise at a $300 billion valuation, the largest private tech funding round on record. The same month it agrees to buy chip designer Ampere for $6.5 billion.

  2. October – November 2025

    Sells Nvidia, again

    On 11 November SoftBank discloses that it sold its entire Nvidia stake in October for $5.83 billion to help fund OpenAI. Its shares fall sharply that month amid fears of an AI bubble.

  3. December 2025

    The OpenAI pledge is completed

    SoftBank finishes funding its OpenAI commitment. OpenAI now sits beside Arm as one of its two largest assets.

  4. June & September 2026

    Asia's richest, then not

    Son briefly passes Mukesh Ambani as Asia's richest person. A selloff on 4 June cuts his fortune by over $13 billion, and he loses about $22 billion in a week. A rout on 14 September takes $8 billion more, leaving him at about $72.5 billion.

∞
2024 – 2026

Recent one-day losses

Most of his wealth is SoftBank stock, so a bad day in Tokyo costs him billions.

Exhibit K · Single trading days
5 Aug 2024
Yen carry-trade unwind; Nikkei's worst day since 1987
−$4.6Bshares −19%
5 Nov 2025
Global selloff on AI valuations; biggest fall of any Asian billionaire that day
−$13.1Bshares −10%
25 Nov 2025
Google's Gemini 3 raises doubts about OpenAI's lead
−$5Bshares ≈ −10%
4 Jun 2026
Tech selloff; loses the title of Asia's richest person to Mukesh Ambani
−$13B+shares −11%
14 Sep 2026
AI stocks fall on calls for a slowdown; net worth about $72.5B
−$8Bshares −10.7%

For scale: the 2000–01 crash took about $70 billion over roughly a year. These single days took $5–13 billion each.

Epilogue

Forty-five years, one bet at a time.

He has lost more money than anyone in history and made it back more than once. In 2026 SoftBank's value rests mainly on two holdings, Arm and OpenAI. Son is 69, still chairman and chief executive, and still saying the biggest bet is the next one.