1. Exxon Mobil Corporation is the world's largest company in terms of market capitalisation. An American multinational oil and gas corporation, Exxon Mobil was formed on November 30, 1999, with the merger of Exxon and Mobil. Headquartered in Irving, Texas, ExxonMobil is one of the largest publicly traded companies in the world. Exxon Mobil is also the world's largest refiner. Mcap: $377.69 billion
2. Apple Inc M-cap: $331.29 billion On the first day of stock trading in 2011, Apple's market capitalisation crossed the $300 billion mark, ending the day at $302.32 billion. Apple shares topped $300 in October, 2010 which put the company's value at about $274 billion. Best-known for the Macintosh line of computers, the iPod, the iPhone and the iPad, Apple has today grown to become one of the world's biggest tech companies. 3. BHP Billiton
M-cap: 254.13 billion BHP Billiton is the world's largest mining company and the largest company in Australia by market capitalisation. It was created in 2001 by the merger of Australia's Broken Hill Proprietary Company (BHP) and the Anglo-Dutch Billiton. BHP Billiton is listed on the London Stock Exchange and is a constituent of the FTSE 100 Index. 4. Petro China
M-cap: 241.58 billion PetroChina Company is the largest oil and gas producer and distributor in China. It was the world's most valuable company in September 2010. 5. Microsoft M-cap: $240.30 billion Microsoft Corporation manufactures, licenses, and supports a wide range of products and services related to computing. The rise of stock in the company's 1986 IPO made an estimated four billionaires and 12,000 millionaires among Microsoft's employees.
6. Petrobras M-cap: $237.72 billion Petrobras is the largest company in Latin America by market capitalisation and revenue. Petrobras controls significant oil and energy assets in 18 countries in Africa, North America, South America, Europe and Asia. 7. Royal Dutch Shell
M-cap: $211.14 billion A global oil and gas company headquartered in The Hague, the Netherlands, it is the largest energy company and the second-largest company in the world in terms of revenues. It is one of the six oil and gas 'supermajors'. 8. China Mobile
M-cap: $200.9 billion China Mobile is one of the most valuable mobile telecommunications companies in the world, listed on both the NYSE and the Hong Kong Stock Exchange. As of 2010, China Mobile has over 570 million customers, one of the world's largest mobile phone subscriber bases. 9. Berkshire Hathway
M-cap: $198.51 billion Founded by Warren Buffett, Berkshire Hathaway oversees and manages a number of subsidiary companies. The company averaged an annual growth in book value of 20.3 per cent to its shareholders for the last 44 years. Berkshire now owns a diverse range of businesses. 10. General Electric
M-cap: $198.12 billion The General Electric Company is ranked as the world's second largest company by Forbes. From aircraft engines and power generation to financial services, medical imaging, and television programming, GE operates in more than 100 countries. 11. Wal-Mart
M-cap: $195.09 billion Wal-Mart Stores, Inc runs a chain of large discount department stores and a chain of warehouse stores. In 2010, it was the world's largest public corporation by revenue, according to the Forbes Global 2000 list. The company was founded by Sam Walton in 1962 has 8,500 stores in 15 countries. 12. Google
M-cap: $192.54 billion Beginning in 1996, Stanford University graduate students Larry Page and Sergey Brin built a search engine called 'BackRub' that used links to determine the importance of individual web pages. By 1998, this took the form of Google, one of the most valuable technology brands.
13. Chevron M-cap: $184.34 billion Chevron Corporation, an American multinational energy corporation is active in more than 180 countries. Chevron is one of the world's six 'supermajor' oil companies. For the past five years, Chevron has been continuously ranked as the one of America's 5 largest corporations by Fortune. 14. Procter & Gamble
M-cap: $184.29 billion A multinational conglomerate, Procter & Gamble manufactures a wide range of consumer goods. Ranked 6th in Fortune's Most Admired Companies 2010 list. The company's revenue in 2010 stands at $78.9 billion. Around 23 of P&G's brands have more than a billion dollars in net annual sales, and 18 other products have sales between $500 million and $1 billion. 15. IBM
M-cap: $183.42 billion International Business Machines, founded in 1911, manufactures and sells computer hardware and software. It offers infrastructure, hosting and consulting services in areas ranging from mainframe computers to nanotechnology. In 2010, Fortune ranked IBM as the 20th largest firm in the United States.