|Headquarters||Seoul, South Korea|
|Key people||Chey Tae-won, Chairman & CEO|
|Products||Energy & Chemicals, Telecommunications,
Trading & Services, Semiconductors, Construction, Shipping
|Revenue||US$ 98.917 billion (2011)|
|Net income||US$ 1.51 billion (2011)|
SK Group (Korean: SK그룹, 에스케이그룹) is the third largest conglomerate (chaebol) in South Korea. The SK Group is composed of 92 subsidiary and affiliate companies that share the SK brand and culture. It changed its name from Sunkyoung Group (Korean: 선경그룹) to SK Group in 1997. SK Holdings ranked 72nd in the 2009 Fortune Global 500. SK Group has more than 30,000 employees who work from 113 offices worldwide. While its largest businesses are primarily involved in the chemical, petroleum and energy industries, it also has South Korea's largest wireless mobile phone service provider, SK Telecom, and provides services in construction, shipping, marketing, local telephone, high-speed Internet, and wireless broadband service WiBro. SK has recently further broadened its range of business to semiconductors, merging Hynix into SK Hynix.
As with many other chaebols, SK Group's chairmanship was 'inherited' from father to son: from its founder the late Chey John-hyun to its present chairman Chey Tae-won (eldest son). Chey Tae-won is married to the daughter of the former South Korean President Roh Tae-woo. In May 2008, he was given a three-year suspended prison sentence for a US$1.2 billion accounting fraud but was pardoned in the same year.
SK Group began when the current founders acquired Sunkyung Textiles in 1953. In 1958, the company manufactured Korea's first polyester fiber on company grounds. It established Sunkyung Fibers Ltd. in July 1969, and started to produce original yarn. In 1973, SK then established Sunkyong Oil, beginning a vertical integration strategy to manage production, "From Petroleum to Fibers”. That same year, the company acquired the Walkerhill Hotel.
In 1976, Sunkyung Corporation received an international trading company license from the Indian government. In December 1980 SK purchased privately run Korea National Oil, making it Korea’s fifth largest conglomerate.  In January 1988, crude oil was imported for processing to Korea from Yemen’s Marib oil field.
In June 1994, SK entered Korea’s telecommunications business by becoming Korea Mobile Telecommunication Service's largest shareholder. In January 1996, SK Telecom launched Korea’s first commercial CDMA cellular phone service in Incheon and Bucheon.
In 2002, SK Telecom successfully launched the world’s first commercial CDMA 1X EV-DO technology, allowing it to offer 3G telecommunications service. In 2004, SK Telecom enabled satellite DMB service by deploying the world’s first DMB satellite. Moreover, in 2006, SK began revitalizing the 3.5-generation mobile phone market and in the following year, completed the construction of the national HSDPA network. In May 2006, SK Telecom started the world’s first commercial 3.5-generation HSDPA service, featuring high-quality video telephony and data transmission, and global roaming access.
In 1998, Management re-branded Sunkyong to SK. In 1999, SK Chemicals developed third-generation (non cross resistant) platinum-complex anti-cancer agent. Also, by focusing its research and development efforts on life sciences, SK Corporation developed YKP1358, a new drug candidate for schizophrenia, in 2003. 
In 2005, SK Networks opened China's first two wholly foreign-owned, gas stations in Shenyang. Then, after exploring Brazilian mining area BM-C-8, SK Corporation developed an oil field where it confirmed the existence of more than 50 million barrels of oil deposits.
SK Gas began developing resources overseas when it participated in two mining areas to the west of Russia’s Kamchatka peninsula in March 2006. In early 2006, SK Networks also developed Ecol-Green, a biodegradable plastic material. Incheon Oil officially started operations using the SK name in March 2006. SK Energy is currently engaged in 27 oil fields in 15 countries worldwide
At the end of 2005, SK Corp. developed a lithium ion battery separator (LiBS) for the first time in Korea, and started selling the product in 2006. In July 2007, SK Group adopted a holding company structure.  Under the re-organization, SK’s main entity, SK Corporation, was split into an investment company, now SK Holdings and an operating company, now SK Energy. The subsidiary companies that now operate under the central SK Holdings umbrella include: SK Energy, SK Telecom, SK Networks, SKC, SK E&S, SK Shipping and K Power
Core Businesses 
SK’s core businesses are energy and telecommunications. Thirteen of SK companies are listed on the Korea Stock Exchange: SK Holdings, SK Innovation, SK Telecom, SKC, SKC Solmics, SK Chemical, SK C&C, SK Networks, SK Gas, SK Communications, SK Broadband, SK Hynix and SK Securities. SK Telecom’s ADRs are also listed on the New York Stock Exchange.
SK restructured in 2007. Under the re-organization, SK’s main entity, SK Corporation, was split into an investment company, now named SK Holdings, and an operating company, now named SK Energy. SK Energy produces batteries for CT&T and Hyundai electric vehicles.
Member Companies 
Some of the member companies that now operate under the SK brand include: SK E&C, SK Energy, SK Telecom, SK Broadband, SK Networks, SK M&C, SKC, SK E&S, SK Chemicals, SK Telesys, SK Shipping, SK Telink, SK Hynix, SK C&C, Walkerhill and SK Wyverns.
SKC (Korean: SKC or 에스케이씨, KRX: 011790), headquartered in Seocho-dong Seocho-gu Seoul, is the leading Korean company in chemical and film industry. SKC was founded and established in 1976 as previous name of "Sunkyung Chemicals Ltd" (Korean: 선경화학 (주)), which was a successor of "Sunkyung Textiles" (Korean: 선경합섬), the matrix for the SK Group nowadays. SKC is one of the best polyester film makers in the world, supplying 10% of worldwide demands with its wide applications including labels, LCDs, and solar cells. With its main plant and R&D center located in Suwon, South Korea, it also operates large capacity of film plant in Georgia, USA. SKC is now developing into one of the leading companies dealing with a variety of eco-friendly, advanced materials for the future energy and chemical industries such as biodegradable films, LEDs and photovoltaic materials.
SK Energy and SK Innovation (Korean: SK 에너지 or 에스케이 에너지 and SK 이노베이션 or 에스케이 이노베이션, KRX: 096770) is a South Korea enterprise. SK Energy is a newly formed entity of the former SK Corporation. As of July 1, 2007, SK Corporation was reorganized into a holding company and operating company, SK Holdings and SK Energy, respectively. In 2011, Petroleum and chemical business spun off. The former is 'SK Energy' and the latter is 'SK Innovation' ‘SK energy’ Founded in 1962 as Korea’s first oil refiner, SK Energy is an energy and petrochemical company with 5,000 employees, KRW 23.65 trillion in sales and 26 offices spanning the globe. The company is Korea’s largest – and Asia’s fourth largest – refiner with a refining capacity of 1.15 million barrels per day, as of 2006. SK Energy is currently engaged in exploration and development activities in 26 oil / gas blocks in 14 nations worldwide.
SK Telecom (Korean: SK 텔레콤 or 에스케이 텔레콤, KRX: 017670) is a South Korean company specializing in offering mobile phone services, wired and wireless combined services. It is part of the SK Group and has evolved from a first-generation analog cellular system operator to become the company that launched the world's first commercial CDMA service. SK Telecom moved on to operate Korea's first 2.5-G CDMA 2000 1X system, followed by the world's first commercial 3-G synchronized cellular system. SK Telecom also launched the world's first 3.5-G HSDPA and SHUPA services.
SK E&C (Korean: SK 건설 or 에스케이 건설) is a Korean construction company founded and established in 1977 with a previous name of Sunkyung Construction (Korean: 선경 건설), headquartered in Gwanhun-dong Jongno-gu Seoul, South Korea. Its brands include SK View, SK Hub, and Apelbaum. The company's CEO is Son Kwan Ho. Industries: Oil & Gas, Petrochemical, Power, Environmental Protection, Industrial, Civil, Building, Housing. Services:Feasibility Study, EPC Service, Project Management, Operations & Maintenance.
SK Holdings (Korean: SK 주식회사 or 에스케이 주식회사, KRX: 003600) is a South Korea enterprise. As of July 1, 2007, SK Corporation was reorganized into a holding company and operating company, SK Holdings and SK Energy, respectively. SK Holdings is a part of the SK Group that focuses on 3 core business interests, Energy & Chemicals, Telecommunications, and Trading & Services. The SK Group is composed of 88 affiliate companies that share the SK brand and culture. In 2006, SK Group recorded combined revenues of $75.8 billion, with exports contributing $26.4 billion of that total. SK continues to expand its global presence, with more than 25,000 employees who work from 113 offices worldwide.
SK Telink (Korean: SK 텔링크 or 에스케이 텔링크 주식회사) is a subsidiary of SK Telecom, was established in April 1998 as an international telephony service provider and has grown into a major player in the international calling market. Under the brand name 00700, the company provides international call services. Building on the commercial long-distance telephony and value-added services launched in 2005, the company began offering Korean SMS in June 2006 in the U.S. The service allows subscribers to send and receive Korean text messages in the U.S., as well as to and from Korea. From 2008 on, SK Telink also started e-Learning service (giving Lectures to customers through the internet) and Foreign Language Test service "BULATS ". BULATS is being used as a main English speaking test for the most of SK Group subsidiaries.
SK Marketing & Company (Korean: SK 마케팅 & 컴퍼니 or 에스케이 마케팅 & 컴퍼니) is a marketing and management company in the SK Group. The company mainly derived from the marketing teams of SK Energy and SK Telecom. It was established on April 4, 2008. The company accounts for several services which were previously provided by SK Energy and SK Telecom, such as the OK Cashbag from SK Energy and the Gifticon service from SK Telecom. They also hold a subsidiary "Ofelis", which is a wedding consulting company.
SK C&C was established in 1991 and is currently one of the "Big Three" IT services companies in Korea. SK C&C has business interests across IT services, including telecommunications, banking & finance, government, public, logistics, and other fields. And the company is expanding its presence overseas. Industries in its product portfolio include GIS, ITS, ERP, national security & defense, postal, e-government, e-learning, postal, and other areas. They also specialize in mobile commerce products and SK C&C USA launched Google Wallet services recently.
Management system 
SK's subsidiary companies all operate under the SK Management System (SKMS) which was developed, articulated and enhanced by SK’s Chairman, Chey Tae-won.
On April 7, 2008, SK Group launched a marketing and management company named "SK Marketing & Company" to pursue Chairman Chey's vision.
See also 
- Fortune 500 2009 List of the World largest Companies
- Ungson & Wong (2008). Global Strategic Management. M.E. Sharpe.
- Mee Kim, Eun (1999). Big Business--Strong State. SUNY Press. p. 91. ISBN 0-7914-3209-2.
- "Diversifying into the Global Marketplace". Korean Integrated News Database System. August 30, 2001.
- Chang, Se-jin (2003). Financial Crisis and Transformation of Korean Business Groups. Cambridge University Press. p. 70. ISBN 0-521-81435-9.
- Kearney (Firm), Kearney, Inc, A. T (2000). Sustaining Corporate Growth: Harnessing Your Strategic Strengths. CRC Press. p. 75. ISBN 1-57444-289-9.
- "South Korea the World’s First 3G Network". 3GNewsroom.com. May 31, 2001.
- "SK Starts New Generation Mobile Phone Service". Korean Integrated News Database System. January 27, 2002.
- "Questions, Expectations over DMB Service". Korea.net. March 20, 2004.
- "SK Telecom Selects LGE, Nortel UMTS/HSDPA Wireless Broadband Technology". Retrieved 2008-01-23.
- "Sunkyong Sets Sails as SK Group Today". Retrieved 2008-01-23.[dead link]
- "Korea’s first locally developed drug gets KFDA approval". Korean Integrated News Database System. July 15, 1999.
- "SK gets nod to test Schizophrenia drug". Korean Integrated News Database System. September 7, 2003.
- "SK Corporation Announces Another IND, Schizophrenia Drug YKP1358". High Beam Research. October 8, 2003.
- "SK Energy Acquires Oil Production Rights in Brazil". Korea.net. July 30, 2007.
- "SK Corp. buys Inchon to raise oil exports". Retrieved 2008-01-23.
- "Uhde will build SKC HPPO unit". Korea.net. May 22, 2006.
- "SK Corp to split as adopts holding co. structure". Reuters. April 11, 2007. Retrieved 2008-01-23.
- "SK Launches Holding Company System". Archived from the original on 2007-09-30. Retrieved 2008-01-23.
- "China Aviation faces 3rd creditor lawsuit". International Herald Tribune. February 24, 2005.
- "New probe hits SK chief". BBC News. September 22, 2003.
- SK site SK