Union-negotiated pension plans have invested tens of billions of dollars in predominantly nonunion or antiunion companies, a study said yesterday.

It said 118 private and public pension plans held $12.6 billion worth of common stock in nonunion companies at the end of 1976.

Because the study includes only 142 of the hundreds of pension plans in this country, its authors said it was fair to conclude that "tens of billions of dollars of union-related pension funds are presently invested in companies that have pursued a deliberate antiunion policy for several decades."

The study was conducted by Corporate Data Exchange Inc., a 4-year-old, nonprofit corporation in New York City. The organization referred to its study as the most comprehensive survey to date of investments by the largest private and public American pension plans.

Among other things, it found that union-negotiated pension funds of the United Auto Workers and the International Union of Electrical Workers have invested $61 million of the stock of Texas Instruments, a company that both unions have tried and failed to organize in recent years.

"In fact, 55 union-related plans were identified as owning more than 8 percent of Texas Instruments' common stock, a potenitally powerful weapon in any union drive. These holdings have not been utilized for gaining leverage over Texas Instruments," the report said.

The report also noted that 86 union-related pension plans have bought $514.7 million worth of stock in Halliburton Co. of Dallas which owns Brown & Root, the world's largest nonunion construction company, based in Houston.