Back in 2012, it was a mystery to many why Chey Tae-won spent $3 billion to buy control of troubled Hynix Semiconductor. Ten years after being bailed out by South Korea’s government, the world’s second-largest chipmaker was losing money and its stock sliding amid a global slump in demand for PCs and memory chips. South Korea’s SK Group, the sprawling conglomerate Chey chairs, had a wireless carrier, an oil and gas company, a hotel operator but no presence in chipmaking. “Pretty much everyone in the financial services industry thought it was a terrible purchase,” says Morningstar Research Director Dan Baker in Hong Kong. SK Holdings’ stock fell 15% between the day in November 2011 the deal was announced and the day it closed the following February. To Chey, though, the rationale was clear. “SK needed something else to grow,” he recalls during a rare interview held on the sidelines of the World Economic Forum’s annual meeting in Davos. “Someone needed to step up. It made sense to me.” SK’s wireless subsidiary, SK Telecom, bought a 21% stake in Hynix from a group of creditor banks, and Chey, already chairman of SK Group and SK Holdings, gained a new title: co-CEO of Hynix, later renamed SK Hynix. Chey’s foray into the volatile chip industry turned out to be one of his savviest investments, timed almost perfectly to take advantage of a nascent global boom in smartphones. SK Hynix earned an estimated $14 billion last year, up 40% from 2017, on revenue of $36 billion—an impressive 39% profit margin. The stock has climbed roughly 150% since SK took control. In September SK Hynix ranked No. 20 on the Forbes Digital 100, an inaugural list of the industry’s top publicly traded companies across 17 countries. Chey ranks No. 7 on the list of Korea’s 50 richest, with a net worth of $4.7 billion. “It has been a fantastic investment given the growth in the memory market,” says Baker. The Hynix deal was also a turning point for Chey, now 58, emboldening him to make the kind of big bets that characterized SK under his father before his death in 1998. Chey demonstrated that confidence last June when SK Hynix joined a group of investors paying $18 billion to buy 49.9% of Japanese chip maker Toshiba Memory. Hynix also created an imperative for Chey to expand. SK Hynix now produces 70% of SK group’s net profits, according to the company, eclipsing its earnings from telecom, oil and chemicals and thereby posing a risk as big as it is successful, given the cyclical nature of the chip business. In a little over two years, therefore, SK group has spent $2.6 billion to venture into a range of new businesses, from ride-hailing apps and biopharma to food and beverages. “We need to explore other areas,” Chey says. “I cannot rely 100% on semiconductors.” SK was born in 1953, when the Korean War had just ended and Chey’s uncle Chey Jong-kun started making polyester. Sunkyong Textiles took advantage of government loans and tax incentives to expand, starting with exports of rayon to Hong Kong (SK is an abbreviation of Sunkyong). When Jong-kun died of lung cancer in 1973 at age 47, his three sons were too young to lead the fast-growing company. In keeping with Korean tradition, his younger brother and Chey’s father, Chey Jong-hyon, took over. Jong-hyon steered SK’s expansion into new industries with the purchase of two companies that now rank among SK’s biggest interests: in 1980, he bought 50% of Korea Oil from former U.S. oil giant Gulf (now SK Innovation), placing SK among Korea’s top five conglomerates, or chaebol, by assets (today it is No. 3 after Samsung and Hyundai). Then, in 1994, he led the $530 million takeover of state-owned Korea Mobile Telecommunications Services, renaming it SK Telecom. In 1998, at the height of the Asian financial crisis, lung cancer claimed the life of Jong-hyon, thrusting his 37-year-old son, Chey Tae-won, into the role of group chairman. “It was a war situation,” Chey recalls. “There was only one thing on my mind: I have to survive.” Chey had been groomed to lead the Korean multinational: while studying at the University of Chicago in the late 1980s, he met his wife, Roh So-young, daughter of former South Korean president Roh Tae-woo. He joined SK in 1989 as a manager at a subsidiary in San Jose, California, moved two years later to the group’s U.S. headquarters in New York and returned to Seoul in 1994 as group managing director. By 1997, he had already been promoted from head of business development to CEO of SK Corp., then the group’s largest subsidiary. Chey cut his teeth on smaller deals: in 2000, he engineered the takeover by SK Telecom of a smaller rival, Shinsegi Telecom, for 2.3 trillion won ($2 billion) in cash and stock. Buying Shinsegi boosted SK Telecom’s market share overnight to 57% from 43%. But Chey’s plans for an overseas push were put on hold when, in 2003, he was sentenced to three years in prison for accounting fraud. He was released after seven months and given a full presidential pardon in 2008. Chey didn’t manage to resume SK’s expansion until 2007, when he turned SK Corp. into a listed holding company, SK Holdings, for SK’s major subsidiaries; it is now the de facto holding company in which Chey and his family hold nearly a 30% stake. Chey then led SK into China, investing in oil exploration in the South China Sea as well as energy and chemicals in Shanghai and Wuhan. Today, the SK group employs 93,000 people in 101 companies and generates an estimated $140 billion in combined revenues. Of these, 16 major companies operate autonomously, yet the CEOs of these firms convene monthly as part of a “Supex Council” to coordinate strategy under the slogan “independent yet united.” When Chey first started looking at Hynix, it was a troubled company with a dominant position in the market for dynamic random-access memory, or DRAM, chips. The nine Korean banks that ended up its largest shareholders after its 2002 bailout had hunted for years for a buyer. U.S.-based chip company Micron Technology bid $3 billion in 2002, only to be rejected by Hynix’s board.