Halliburton ( HAL) agreed to settle a class-action lawsuit, combining about 20 shareholder suits, that alleged the company used aggressive accounting techniques and overstated its revenue from 1999 through 2001.

The oil services company and representatives of the plaintiffs signed a memorandum of understanding to settle the cases that had been consolidated before a federal court in Dallas and a shareholder derivative suit pending in the same court. A second derivative lawsuit filed in Harris County, Texas, has been dismissed.

Three of the four lead plaintiffs in the securities actions have agreed to the settlement terms and the fourth is evaluating the matter, Halliburton said.

All of the cases initially rose out of questions regarding Halliburton's accounting for revenue associated with unapproved claims and change orders on long-term fixed price construction projects.

In a press release Friday, the company said that "the memorandum of understanding more broadly covers all claims, however denominated, arising out of a purchase of Halliburton stock during the class period of May 18, 1998, through May 28, 2002, and all derivative claims that could have been asserted against the defendants."

Terms of the settlement weren't disclosed, but Reuters and the Associated Press reported the amount at $6 million. The company said only that the settlement payment, including all costs and attorneys' fees, "is immaterial and will not impact Halliburton's second-quarter results." The terms of the settlement include provisions calling for the release from liability of all current and former Halliburton officers and directors who were named in the suits.

Halliburton didn't admit to any wrongdoing in settling the cases. The settlement is subject to, among other things, court review and approval.

The accounting practices in question involved cost overruns on construction projects in the late 1990s and led to a Securities and Exchange Commission investigation of Halliburton that's still ongoing. The company has been accused of overstating revenue by $445 million.

Shares of Halliburton were up 45 cents, or 2%, to $23.60 in recent New York Stock Exchange trading.