Coverage of corporations or activities directly involving them took over half of all national news coverage in the period March 6 through April 2, the Conference on Issues and Media reports.

This is the first time since the measurement of this data began in 1985 that news exposure of corporations has so heavily dominated news media output over a full four-week period, said John Merriam, the company's chairman.The Conference on Issues and Media Inc., based in Alexandria, Va., publishes the National Media Index as well as two newsletters, Executive Trend Watch and Corporate Exposure.

The national index has been maintained since 1982 and regularly includes more than 500 current issues and 700 corporate images.

Three major stories, the Eastern Airlines strike, criminal proceedings involving officials of Drexel Burnham Lambert, and the oil spill from an Exxon tanker off Alaska, contributed nearly a fifth of total corporate coverage, or 9.9 percent of all national coverage in the period, according to CIM.

The Eastern strike received 5 percent, Exxon, 4.04 percent, and Drexel 0.85 percent. All three stories had a negative impact on corporate image, CIM noted.

The rising level of corporate news exposure is also marked by a heavy portion of news negative to the images of individual corporations and industries.

For the period, 19.5 percent of all media coverage was scored as negative, or nearly two out of every five column inches or TV minutes. CIM said this marked an unusually heavy portion of bad news for corporations, much of it coming from the three leading stories.

"The record 51 percent level of corporate news exposure marks the continuation of a trend that began in early 1987," Merriam said.

"With rising focus on private sector activity, corporations are getting more news attention because people increasingly see the corporate sector as the center of important action in the country," Merriam said.