Draft:Largest British Companies in History by Market Capitalisation

This list comprises of the largest British companies in history by market capitalisation when adjusted for inflation at their peak valuation. This list will include all 26 UK-based companies which have accumulated a valuation of $70 billion or more at their peak 23 of these companies have their primary listing on the London Stock Exchange, 2 on the New York Nasdaq and finally, 1 on the New York Stock Exchange.

Key Points:

The 2 Nasdaq listed companies include Cambridge based tech company Arm Holdings. As well as Woking based Linde plc which as of May 2025 has been the largest chemicals and industrial gases company in the world since 2018. While professional services and insurance giant Aon plc is the only company that meets the lists criteria which is listed on the New York Stock Exchange.

Four dual-national companies are represented on the list including, AstraZeneca an Anglo-Swedish company, Unilever an Anglo-Dutch company, Rio Tinto an Anglo-Australian company and Glencore a Anglo-Swiss company. Although all 4 companies have primary listing on the London Stock Exchange, and are registered British companies. With all bar Glencore having their Global Headquarters in the United Kingdom.

Additionally, Shell followed a similar Anglo-Dutch dual-national structure until its significant corporate restructuring and simplification in January 2022 when it’s A and B shares were merged into a single line. It moved it soul primary listing to London from a London-Amsterdam dual-listing and its universal headquarters to London from its London-Amsterdam dual-headquarters format.

Moreover, HSBC Holdings despite being a UK-based universal investment bank headquartered in Canary Wharf, London, over 55% of its assets are thought to be in the Asian Market with around 70% of its profits coming from Asia as well. It holds a dual primary listing on both the London and Hong Kong Stock Exchanges despite being a UK registered and regulated company.

Rank	Company	Date of Peak	Peak Market Cap (Billions USD)	Market Cap May 2025 (Billions USD)	% Change
1	Vodafone Group	March 2000	340.79	25.82	-92.4
2	AstraZeneca	August 2024	271.67	217.08	-20.1
3	HSBC Holdings	October 2007	270.15	211.26	-21.8
4	BP	April 2006	248.84	76.87	-69.1
5	Linde	October 2024	232.28	216.04	-7.0
6	Shell	July 2024	229.21	197.44	-13.8
7	Arm Holdings	July 2024	189.86	138.03	-27.3
8	GSK	July 2001	181.70	77.78	-57.2
9	Unilever	December 1998	178.47	155.27	-13.0
10	British American Tobbaco	January 2018	156.45	97.34	-37.8
11	Rio Tinto	June 2008	149.51	101.22	-32.3
12	BT Group	December 1999	143.58	22.29	-84.5
13	Diageo	January 2022	128.05	63.61	-50.3
14	NatWest Group	October 2007	124.18	56.23	-54.7
15	RELX	May 2025	103.49	103.49	0.0
16	Lloyds Banking Group	February 2014	98.31	63.01	-35.9
17	Barclays	January 2007	96.27	63.59	-33.9
18	Anglo American	June 2008	92.91	34.08	-63.3
19	Rolls Royce Holdings	May 2025	91.53	91.53	0.0
20	Glencore*	April 2022	91.12	43.49	-52.27
21	Aon	March 2025	88.37	78.37	-11.3
22	London Stock Exchange Group	May 2025	81.22	81.22	0.0
23	Tesco	October 2007	79.66	33.60	-57.8
24	National Grid	May 2025	71.89	71.89	0.0
25	Reckitt Benckinser	August 2020	71.76	44.54	-37.9
26	BAE Systems	May 2025	70.56	70.56	0.0

Causes of Decline:

Internet Bubble

Firstly, the 2 companies on the list which have experienced the highest percentage of decline from their peak are Vodafone Group which has lost 92.4% and BT Group which has lost 84.5%. Both these companies are British telecommunications and Internet providers. They both peaked in the hundreds of billions and in same 3-month period around the year 2000. Whereas now they are both valued around the mid-20s of Billions displaying clear parallels between the two corporations.

This period of extreme success is know as the internet bubble or Dot-com bubble which occurred between 1997-2003 when the limit and profitability of the internet and telecoms was still unknown. A ‘bubble’ in investing is when the price goods or services provided by a company rises far beyond their real value or profitability. In this case the internet as investors and internet companies were not aware of the limits of the industry and how much money could be made.

This pattern was seen all over the world such as America’s Yahoo or Germany’s Deutsche Telekom which both saw their market cap rise into the hundreds of billions before facing huge decline post 2000.

Financial Crisis

The 2008 Financial Crisis saw the decline or partial nationalisation of all four of the UK’s Big 4 banks. HSBC was the only one of these to avoid nationalisation, despite it experiencing a 64% drop in value from over $270bn to just $97bn.

However, the other 3 banks didn’t fend so well with NatWest eventually having over 84% of its shares bought out by the UK government to save the company from bankruptcy as its market valuation dropped from over $124 billion to just $12 billion at the worst of the crisis a 90% drop in capitalisation.

While Barclays avoided British government nationalisation it saw over 31% of its shares be bought by the Qatari state to stabilise the ship and raise capital. Barclays have once again never fully recovered or reached the same heights as it did pre-2008.

While Lloyds Banking Group saw 43% of its shares bought out by the Government in 2009 to prevent its collapse and faced a 80% drop in valuation. It is the only one of the Big 4 banks to have fully recovered from the crisis with it seeing its all time peak in 2014, 5 year on from the worst of the crisis reaching 53% higher than its pre-2008 valuation.