Merry-Go-Round Enterprises, the Maryland-based retail clothing chain whose sales, earnings and stock price have skyrocketed recently, plans a public offering of 2.15 million common shares -- 850,000 to be sold by the company and 1.3 million by certain non-employee stockholders. The stock, which trades on the New York Stock Exchange, closed yesterday at $25.87 1/2, down $1.62 1/2.

Texas Instruments is negotiating to buy a 60-acre parcel of land in Owings Mills owned by the state of Maryland so that it can consolidate five smaller facilities in the area, company officials said. The company wants to build a facility with up to 200,000 square feet of space and have the capability of expanding later.

USAir will plunge further into the intensifying international flight market through marketing alliances with foreign airlines in an effort to offset its sluggish domestic business, Chairman Edwin Colodny said. The airline also will delay deliveries of new planes from Boeing and slow the shelving of older planes to increase its flexibility, he said.

Wheeling-Pittsburgh Steel's amended reorganization plan has been approved by a bankruptcy judge. The plan is supported by all major players except company employees and could pave the way for a new union contract.

McDonald's will post complete nutritional information, including fat and sodium levels, on all products at its restaurants by the end of July.

Systems Center, a Reston-based IBM software developer, and Software Developments International Pty. of Australia completed a $43 million transaction in which Systems Center issued 696,930 shares of its registered common stock in exchange for all outstanding SDI common stock. SDI became a wholly owned subsidiary of Systems Center.

Star Technologies of Sterling a producer of advanced computing graphics processors, completed a $15 million recapitalization program that will allow the company to retire its $11 million subordinated debt and provide it with additional working capital.

Delta Air Lines asked the Department of Transportation for permission to offer service to Hong Kong from one or more of three gateway cities -- Los Angeles, Honolulu and Portland, Ore. REGULATION

Boise Cascade agreed to pay a $350,000 penalty to the Environmental Protection Agency for starting a $535 million expansion project at its International Falls, Minn., paper mill without undergoing review or obtaining a construction permit. CONTRACTS

Martin Marietta received a $145.7 million Navy contract for submarine sonar equipment.

Earth Technology received a $47 million Air Force contract for missile engineering services.