Money & Finance › Markets of the world › World stock markets: about $158 trillion, 44% of it in the US
London Stock Exchange (LSEG) and the FTSE 100
Coffee-house roots 1698; FTSE 1984· Institution or agency
Fact, law or dataA rule, statute, definition or measured number.
Britain's main stock market, run by the London Stock Exchange Group (LSEG); its FTSE 100 index tracks the 100 largest UK-listed companies.
See it on the Money & Finance map →How it works
Share dealing began in City coffee houses, where John Castaing posted prices from 1698; the exchange formally opened in 1801. The FTSE 100 started in January 1984 at 1,000 and first topped 10,000 in January 2026. It is heavy with banks, oil, miners and drugmakers such as HSBC, Shell and AstraZeneca, whose sales are mostly abroad. LSEG now earns most of its revenue from data after buying Refinitiv in 2021, and it controls the LCH clearing house.
Why it matters
London is Europe's biggest financial center, yet its share of global listings has shrunk as companies such as Arm, CRH and Flutter chose New York instead.
Facts, rules and data
LSEG annual reports, FTSE Russell index data, exchange listing statistics and histories of the Stock Exchange; the 2024 listing-rule overhaul is published by the Financial Conduct Authority (FCA).
Debates and risks
Whether the July 2024 listing reforms and pension-fund changes can revive London IPOs and stop more companies moving their main listing to the US.
Connections (3)
▸London Stock Exchange (LSEG) and the FTSE 100 owns LCH, a giant among Clearing houses: DTCC, the Options Clearing Corp. and CME ClearingFact, law or data
The connection
LSEG became majority owner of LCH in 2013. LCH's SwapClear service clears most of the world's centrally cleared interest-rate swaps, standing between banks on trillions of dollars of notional value each day and holding their margin. That makes a London company a core part of the global plumbing for dollar and euro swaps.
When and why
London; LCH formed in 2003 from the London Clearing House and France's Clearnet, and LSEG bought control in 2013.
How we know
LSEG annual reports, LCH volume statistics, and Bank of England supervision documents on central counterparties.
Debates and risks
After Brexit, how long EU regulators will let EU banks clear euro swaps in London, and how much new EU rules shift to Frankfurt.
▸Euronext: the Amsterdam, Paris and Milan exchanges is bigger by listed value than London Stock Exchange (LSEG) and the FTSE 100Fact, law or data
The connection
Euronext's markets list about €6.8 trillion of companies, well above London's total. Paris alone passed London as Europe's most valuable stock market in late 2022, helped by luxury giants such as LVMH, while Brexit, a weaker pound and companies moving listings to New York shrank London's share.
When and why
Paris and London, November 2022, when Bloomberg data showed French stocks worth more than British ones; Euronext's lead grew after it bought Borsa Italiana in 2021.
How we know
Market-capitalization statistics from Euronext, LSEG, the World Federation of Exchanges and Bloomberg.
Debates and risks
Rankings shift with currencies and counting methods, and London still leads Europe in foreign listings, bond trading and currency trading.
▸London Stock Exchange (LSEG) and the FTSE 100 competes for listings with Stock exchanges: NYSE and NasdaqFact, law or data
The connection
Companies list where they expect the most investors and the highest valuations. Since 2022, Arm, CRH, Flutter, Ferguson and others chose New York for their main listing, citing deeper investor pools. Britain answered in July 2024 by merging its listing categories and relaxing rules on dual-class shares.
When and why
London and New York, 2022–26; Wise shareholders voted in 2025 to move its main listing to the US.
How we know
Company announcements, LSEG and FCA statements, and IPO league tables.
Debates and risks
Whether London's slide is about rules, valuations or UK pension funds' shift away from British stocks.