The nation's largest companies continue to move away from providing traditional pensions, with just over a third now offering the benefit to newly hired workers, a sharp drop over the past few years, according to a survey released Wednesday.

Of the nation's 100 largest companies, just 37 offered a traditional pension plan to new hires in 2005, down from 42 the previous year and 50 in 2002, according to benefits consulting firm Watson Wyatt Worldwide. In 1985, 89 of the largest 100 companies offered pensions.

At the same time, more companies are providing new hires with only a 401(k) or similar defined contribution plan, with 36 employers now going that route, up from 25 in the previous year and 17 in 2002. Some of those companies have shifted to 401(k) plans after giving up so-called hybrid pension plans.

Hybrids, the best known of which are cash balance plans, have come under fire from older, more experienced workers at some companies who say they discriminate in favor of younger employees. The plans offer a guaranteed benefit like a traditional pension, but are portable like a 401(k). Many such plans, however, reduce the rate at which older workers accrue benefits at the very time when traditional pensions award more substantial benefits.

Employee lawsuits have left cash balance plans on shaky ground. At the same time, companies have cringed in the past few years at having to make massive contributions to underfunded plans because of a confluence of poor stock market returns and very low interest rates. Meanwhile, the slowness of Congress to move forward on measures intended to improve funding of pension plans and clarify the legal questions around hybrid plans have led some employers to get out of offering pensions.

In the past year, prominent companies including IBM Corp. and Verizon Communications Inc. have announced plans to freeze pension plans and shift all workers into defined contribution plans. Many other companies have made a more limited move, allowing current workers to continue earning pension benefits but restricting them for new hires.

The move away from the guarantees built in to traditional pensions could spell trouble for companies and their workers, said Kevin Wagner, a director in Watson Wyatt's retirement practice. ''What's going to happen with the 401(k) environment is if people aren't taking care of their retirement needs when they're 25 years old, when they're 30 years old, nobody else is going to do it for them,'' Wagner said.

As companies shift to such a system that offers workers no guarantees, that will also increase the risk to employers, making it difficult to know when workers are going to retire, he said. Companies with only defined contribution plans could also find it harder to hold on to their workers, Watson Wyatt said. Traditional pensions offer workers a strong incentive to remain with an employer, while the balance in a 401(k) is easily transferrable.

While the companies on the list of the 100 largest change over time, employers that have remained on the list show the same likelihood for curtailing benefits as new additions, Watson Wyatt found. Wagner said the move away from traditional pensions was most pronounced at the very largest companies. But the companies in the next tier are likely to follow suit, he said.