ECONOMY

T-bill yields rose at the government's weekly auction. The Treasury sold 13-week bills at an average discount of 7.41 percent, up from 7.23 percent last week, and 26-week bills at an average discount of 7.31 percent, up from 7.19 percent. The investment rate was 7.66 percent on the 13-week bills, 7.70 percent on 26-week bills.

COMPANIES

Western Union employees rejected a 90-day contract extension as the company replaced at least half of its 2,500 union workers with temporary employees, a spokesman for the Communication Workers of America said. Union lawyers later filed an unfair labor practices complaint with the NLRB over the lockout.

Bethlehem Steel plans to sell its railroad freight car division as part of an effort to divest assets unrelated to its basic steel-making operations.

Chase Manhattan is offering longtime U.S. employees severance payments to leave their jobs early as the nation's second-biggest banking company begins efforts to trim costs by $300 million.

Sears recently discussed merging its entire merchandising operation with rival Montgomery Ward & Co., with Sears as the surviving company, but the talks ended without agreement, two Sears board members said. Sears also denied a report that Chairman Edward Brennan has been told by the board of directors to turn around retail operations in six months or face the prospect of losing his job.

Nova Pharmaceutical of Baltimore filed a registration statement with the SEC covering its proposed issuance of 2.5 million shares of convertible exchangeable preferred stock.

Wheeling-Pittsburgh Steel closed coke ovens and blast furnaces and braced for a strike Thursday by 5,500 union workers in Ohio, West Virginia and Pennsylvania. The company took the steps after the United Steelworkers rejected a contract offer.

INTERNATIONAL

Mobil agreed to buy Esso Australia for an undisclosed price, a move that will raise its share of the Australian oil market to 20 percent.

CONTRACTS

Martin Marietta received a $185 million contract from GE Aircraft Engines to produce an additional 400 thrust reversers for CF6-80C2 jet engines. The work will be done in Baltimore.

Computer Sciences Corp. received a $31.9 million Air Force contract to upgrade the Military Airlift Command's information processing system.

REGULATION

Crestar Bank of Richmond received Fed approval for its merger with National Bank of Northern Virginia of Sterling. Crestar and the one-branch National Bank are both subsidiaries of Crestar Financial of Richmond.

Donald Trump's request to keep secret details of his recent financial bailout was rejected by the New Jersey Casino Control Commission. But the commission gave Trump until this afternoon to obtain a court order keeping the documents secret pending a ruling by a state appellate court.