Mikhail Borisovich Khodorkovsky, sometimes known by his initials MBK, is an exiled Russian businessman, oligarch, and opposition activist, now residing in London. In 2003, Khodorkovsky was believed to be the wealthiest man in Russia, with a fortune estimated to be worth $15 billion, and was ranked 16th on Forbes list of billionaires. He had worked his way up the Komsomol apparatus, during the Soviet years, and started several businesses during the period of glasnost and perestroika in the late 1980s. In 1989, he became Chairman of the Board of Bank Menatep, which he founded. After the dissolution of the Soviet Union, in the mid-1990s, he accumulated considerable wealth by obtaining control of a number of Siberian oil fields unified under the name Yukos, one of the major companies to emerge from the privatization of state assets during the 1990s.