NEW YORK (CNN/Money) - General Motors Corp. and Ford Motor Co. are expanding the use of anti-rollover technology on their popular sport/utility models, addressing a major safety risk for the vehicles.

Only 3 percent of vehicle accidents involve rollovers, but they account for a third of accident fatalities.

The technology helps drivers maintain control of their vehicle during extreme steering maneuvers, such as a sudden swerve to avoid an obstacle, using automatic braking of individual wheels to prevent the vehicle from changing direction too quickly or not quickly enough, which keeps it headed in the driver's intended direction.

The Insurance Institute for Highway Safety released a study last month that this kind of technology can reduce the risk of an SUV being in a fatal accident by more than a third.

GM announced Thursday it is making electronic stability control standard on 1.3 million sport utility vehicles beginning immediately many of its full-size SUVs, followed by midsize SUVs in 2005.

The models getting the anti-rollover technology immediately are the Chevrolet Tahoe, Suburban and Avalanche and GMC Yukon and Yukon XL, while the Chevrolet TrailBlazer, and TrailBlazer EXT; GMC Envoy, Envoy XL and Envoy XUV, Hummer H3 and Saab 9-7X and Buick Rainier will get the new safety equipment in 2005. The Hummer H2 will get ESC in 2006.

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Some of the company's highest-priced SUVs, the Cadillac Escalade, Escalade EXT and ESV and the GMC Yukon Denali and Yukon XL Denali, already have the electronic stability control.

Ford said that by the end of 2005, more than half a million of the company's SUVs will be equipped with roll stability control, its version of the anti-rollover technology. The company said the equipment is already standard on 2005 Ford Explorer, Lincoln Navigator, Lincoln Aviator, Mercury Mountaineer and Volvo XC90, and available on 2005 Ford Expedition.

The equipment debuted on the 2003 Volvo SUV and it was expanded to Lincoln SUVs for the 2004 model year. It also plans to expand it to the 2006 model year Econoline 15-passenger wagon.

SUVs have a higher risk of rollover in accidents than standard car models or even some other light trucks because of a higher center of gravity. Only 3 percent of all vehicle accidents involve rollovers, according to the National Highway Traffic Safety Administration (NHTSA), but one third of vehicle fatalities are tied to rollover accidents.

The NHTSA gives SUVs with the equipment better safety ratings for rollover avoidance.