WASHINGTON (CNN) - It may just be pocket change for the richest man in the world, but Microsoft Chairman Bill Gates has been fined $800,000 by the federal government for violating an antitrust rule.

Will the world's richest man feel an $800,000 fine?

The technical incident has nothing to do with the government's massive antitrust battles with Microsoft (MSFT: Research, Estimates).

Gates, whose fortune has been estimated at more than $40 billion, ran afoul of the Federal Trade Commission and the Justice Department's Antitrust Division for his purchases of stock in a drug company and a waste-hauling firm.

The Justice Department said Gates has agreed to pay the civil penalty to settle a charge that he violated "premerger reporting requirements."

In a civil suit filed in federal court in Washington Monday, the department said Gates' error stemmed from his acquisition of more than $50 million in voting stock in ICOS (ICOS: Research, Estimates), a drug maker, in May 2002.

The government said Gates did not qualify for an exemption to federal notification requirements because he intended to participate in the business decisions of ICOS through his long-standing membership on that company's board of directors.

The Hart-Scott-Rodino Act of 1976 imposes notification and waiting period requirements on individuals and companies over a certain size before they can complete acquisitions of stock or assets valued at more than $50 million, the Justice Department said.

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"The case filed today is not related Gates' position in Microsoft Corp. or the department's antitrust litigation with the company," the department said in a statement.

The Federal Trade Commission said it had warned Gates about a similar reporting infraction when his personal investment trust bought shares of Republic Services Corp. (RSG: Research, Estimates) in November 2001. The acquisition brought his stake to more than 10 percent of the outstanding shares of the waste-hauling company.

Antitrust rules require that entities must file with the government when their holdings exceed 10 percent of a company's stock.