Yukos has been hit again and again by Russian authorities
As part of a sweeping restructuring of the oil industry, Yukos is created by merger of two state companies - Siberian oil producer Yuganskneftegas and Volga refining company Kuibyshevnefteorgsintez.
Still in state hands, Yukos comes close to bankruptcy amid falling output and rising debt; it owes the government alone $3.5bn.
Through a series of share offers, Yukos becomes the first fully privatised integrated oil company in Russia. Mikhail Khodorkovsky, a billionaire whose main fortune is in banking, acquires the firm for a sum variously put at between $200m and $1.5bn.
Mr Khodorkovsky launches a major restructuring and modernisation programme, with the aim of making Yukos one of the few large Russian to match international standards for corporate behaviour and financial stability. The idea is first mooted of merging with Sibneft, another large producer then controlled by billionaire Boris Berezovsky.
Yukos launches a corporate governance charter, and publishes its accounts to international standards. In 1999, the company had been punished by regulators after neglecting to file its quarterly results.
At the same time, newly-elected President Vladimir Putin strikes a deal with 20 of the "oligarchs" of the 1990s, including Mr Khodorkovsky. According to Moscow rumour, tycoons are told their business interests will be allowed to flourish, as long as they stay out of politics.
Yukos shares are listed in New York, London, Frankfurt, Berlin and Munich. Yukos becomes a major supplier to China after the acquisition of a refinery and other assets in the Russian Far East.
In the late 1990s, Yukos had truly global ambitions
The company's global ambitions step up a gear, with the acquisition of Lithuania's main oil company, a move into Slovakia, and plans to develop an pipeline to China.
Mr Khodorkovsky gets into his first public row with the Kremlin, disagreeing over state control of the pipeline industry. He complains publicly about corruption, and begins openly funding various opposition parties, including the communists.
2 July, 2003
Platon Lebedev, a major Yukos shareholder, is arrested and accused of having illegally acquired shares in Apatit, a fertiliser company, in 1994. Mr Khodorkovsky is questioned and released two days later.
16 July, 2003
Russian tax authorities say they are to audit Yukos's books, as the investigation into the Apatit deal is dramatically widened. Yukos's offices are raided and records taken away.
25 October, 2003
Mr Khodorkovsky is arrested, flown to Moscow and charged with various counts of fraud of tax evasion.
30 October, 2003
The Russian authorities freeze the 44% stake in Yukos owned by Menatep Bank, Mr Khodorkovsky's main investment vehicle. Previously, Yukos had announced a $2bn dividend to shareholders - an attempt to extract money from the firm ahead of any possible confiscation.
3 November, 2003
Mr Khodorkovsky resigns as chief executive of Yukos in favour of Simon Kukes, and is reported to have handed his interest in the company over to associates outside Russia. Mr Kukes tries to distance Yukos from Mr Khodorkovsky, pouring cold water on previous plans to sell the company to a foreign investor.
30 December, 2003
Yukos is hit with a bill for $3.5bn, representing tax allegedly unpaid in 2000.
Mr Khodorkovsky is still in prison; his trial drags on
11 March, 2004
More than $5bn belonging to Yukos shareholders is frozen in Switzerland, after Moscow argues that the money has been stolen. Arrest warrants are issued for another 10 of the company's senior associates.
27 May, 2004
Yukos warns it will have to file for bankruptcy if the $3.5bn tax demand is pushed through.
16 June, 2004
Mr Khodorkovsky's trial finally begins, with the threat of up to 10 years in prison. The case is immediately adjourned.
6 July, 2004
Yukos gets more time to pay its tax bill, but is hit by a fresh demand for $3.4bn in unpaid taxes from 2001.
12 July, 2004
The trial resumes. Prosecutors argue that Mr Khodorkovsky and Mr Lebedev ran an "organised criminal group". Mr Khodorkovsky says the charges are "absurd".
20 July, 2004
Russian bailiffs say they will sell off Yuganskneftegas, Yukos's main production unit, to pay off its back taxes.
2 August, 2004
Tax inspectors begin looking at Yukos's 2002 accounts, raising fears of a third multi-billion-dollar demand.
1 November, 2004
Yukos is reportedly hit with another $10bn tax bill, this time relating to 2002. Doubts remain over the fate of Yuganskneftegas, which is rumoured to be on the point of a sale. Yukos says its production will imminently come to a halt unless the situation surrounding any sale can be clarified.
25 November, 2004
All Yukos's top executives are reported to have left Russia, apparently fearing arrest.
10 December, 2004
Three firms, including dominant gas producer Gazprom, submit bids for the 19 December auction of Yuganskneftegas.
15 December, 2004
Yukos files for bankruptcy in the US, in an attempt to derail the Yuganskneftegas sale.
16 December, 2004
A US bankruptcy judge grants a temporary injunction blocking the Yuganskneftegas sale. But Russian officials say the Houston court has no jurisdiction in the case and call the ploy a "nonsense".
19 December, 2004
Auction of Yuganskneftegas in Moscow, which is sold to little-known firm Baikalfinansgroup for $9.35bn.
23 December, 2004
State-owned oil firm Rosneft - itself preparing for a merger with state-controlled gas group Gazprom - buys Baikal, thus acquiring Yuganskneftegas. The unit is effectively renationalised.
12 January, 2005
Mikhail Khodorkovsky hands over controlling stake in Yukos parent firm Menatep to fellow shareholder Leonid Nevslin, by now resident in Israel.
9 February, 2005
Menatep says it plans to sue Russian government for $28bn. Experts doubt it can succeed.
14 February, 2005
Yukos sues Rosneft, Baikal, and Gazpromand one of its units, claiming damages of $20bn for their alleged role in the Yuganskneftegas sale.
25 February, 2005
US court dismisses Yukos' bankruptcy petition.
15 March, 2005
Rosneft sues Yukos over an $11bn back tax bill allegedly owed by Yuganskneftegas.
25 March, 2005
Ex-Yukos security chief Alexei Pichugin convicted of murder and attempted murder.
19 April, 2005
Russian court freezes more of Yukos' assets as its own former unit Yuganskneftegas accuses it of having paid below-market prices for its oil and demands $6bn in compensation.
27 April, 2005
Judges postpone their verdict on Mikhail Khodorkovsky till 16 May.
31 May, 2005
After 12 days of summing up the trial, the judges find Mikhail Khodorkovsky and Platon Lebedev guilty of six charges including tax evasion and sentence them to nine years in prison each.