ECONOMY

Yields on 30-year Treasury bonds rose to the highest level in more than a year as the government concluded its quarterly refunding. The average yield was 8.87 percent, up from 8.84 percent at the last auction May 10.

Money market mutual fund average yields fell. Average seven-day simple yields were 7.50 percent, down from 7.56 percent the previous week, and 30-day simple yields were 7.58 percent, down from 7.62 percent.

COMPANIES

Unisys expects to lay off 200 Pennsylvania workers from defense group operations in Valley Forge by 1991.

A GM strike by 3,200 workers at a Flint, Mich., plant caused a GM vehicle assembly plant in Ohio to shut down because of a parts shortage. GM said it expects more plants to close today and next week if the walkout continues.

Renault has extended the deadline on its $6-per-share tender offer for Mack to Aug. 22.

Ford, Mazda and Sanyo announced plans for a $75 million joint venture to manufacture automotive radio products in Malaysia.

ACQUISITIONS

Systems Center and Unitech Software, both Reston-based, agreed to merge through a stock swap valued at $4.5 million to $6.8 million.

REGULATION

The Federal Reserve Board approved the applications of C&S/Sovran Corp. and Sovran Financial Corp. to act as an agent in the private placement of securities.

PEOPLE

Donald Trump can keep secret the documents that contain the terms of his financial restructuring. An appeals court judge reversed a decision by the New Jersey Casino Control Commission that would have made public those details.