Computer chipmaker Intel has been fined a record 1.06bn euros ($1.45bn; £948m) by the European Commission for anti-competitive practices, BBC reported.
It dwarfs the 497m euro fine levied on Microsoft in 2004 for abusing its dominant market position.
The Commission found that between 2002 and 2007, Intel had paid manufacturers and a retailer to favour its chips over those of Advanced Micro Devices (AMD).
Intel has announced that it will appeal against the verdict.
"Intel takes exception to this decision. We believe the decision is wrong and ignores the reality of a highly competitive microprocessor market," Intel chief executive Paul Otellini said.
"There has been absolutely zero harm to consumers. Intel will appeal," he added.
The investigation followed complaints by AMD in 2000, 2003 and 2006.
The Commission said that Acer, Dell, HP, Lenovo and NEC had been given hidden rebates if they only used Intel chips.
It also found that Media Saturn, which owns Europe's biggest consumer electronics retailer Media Markt, had been given money so that it would only sell computers containing Intel chips.
"Intel has harmed millions of European consumers by deliberately acting to keep competitors out of the market for computer chips for many years," said Competition Commissioner Neelie Kroes.
"Such a serious and sustained violation of the EU's antitrust rules cannot be tolerated."
Last year, Intel made 80.5% of the microprocessors in PCs, while AMD made 12% of them.
The Commission has also ordered Intel "to cease the illegal practices immediately to the extent that they are still ongoing".
In addition to providing rebates to manufacturers that bought almost entirely Intel products, the Commission found that the chipmaker had paid them to postpone or cancel the launch of specific products based on AMD chips.
Ms Kroes joked in her own news conference that Intel would now have to change its latest advertising slogan from "sponsors of tomorrow" to "the sponsor of the European taxpayer".
Both Intel and AMD are based in California. Intel has 83,900 staff worldwide and has a market value of $85.4bn.
AMD employs about 11,000 people and has a market value of $2.6bn.
"Despite its strong defence, Intel is facing a wall of regulatory resistance to its business practices around the world, with antitrust infringement decisions against it now in Japan, Korea, and the EU, while the US authorities are investigating Intel as well," said David Anderson, a lawyer at Berwin Leighton Paisner.
"It is a major decision that shows the Commission is serious about curtailing abusive behaviour of dominant companies, especially in the high-tech sector."
...