December 31, 1986

The Unisys Corporation, the computer company formed by the merger of the Burroughs and Sperry Corporations, said yesterday that it would take a write-down of between $250 million and $275 million, causing a ''substantial'' fourth-quarter loss. Company officials say they did not know if the write-down would wipe out the profits of Unisys for the year. Such a write-down was expected in the wake of numerous closings of plants and offices belonging to the two merged companies.

Soviet Bars TV Greetings A renewed exchange of televised New Year's greetings by President Reagan and Mikhail S. Gorbachev was called untimely by Moscow.

The Government index intended to predict the economy surged 1.2 percent in November, the biggest advance in seven months, the Commerce Department reported today. The latest reading, which was somewhat stronger than expected, was widely regarded as pointing to continued economic growth in 1987. But analysts differed markedly about how vigorous the fifth straight year of expansion was likely to be. Many contended that the sharp November jump in the index of leading indicators overstated the economy's strength, partly because the new tax law that takes effect this week has been spurring demand recently.

Ending a 19-day special session that had set suburban and New York City lawmakers against each other, the State Legislature voted today to finance a rebuilding of the city's mass-transit system and a three-year freeze of its fares. The vote averted the immediate fare increases on the city's subway, bus and commuter rail lines that had been threatened by the Metropolitan Transportation Authority. The legislation won approval after Democrats, in an effort to appease Republicans from suburban areas, agreed to increased spending for the rebuilding of highways and to direct state aid for commuter rail lines. A Postponed Decision Although the legislation averts immediate fare increases and allows a five-year $8.6 billion M.T.A. capital-construction program to begin on the city's transit system and commuter rail lines, it does not fully resolve the transit matter. After weeks of proposals and counterproposals, the Legislature was unable to agree on how to raise the final $735 million for the program, and the measure puts off until March 15 that politically divisive decision. Governor Cuomo's original proposal, for a nickel-a-gallon increase in the gasoline tax, was blocked by suburban Republicans.

The Morgan Grenfell Group, a leading London merchant bank, quit today as advisers to Guinness P.L.C., the brewer that is the target of a Government investigation. And Roger Seelig, a director of Morgan Grenfell's securities subsididary who was considered one of the stars of its mergers and acquisitions staff, resigned today because of questions raised about his role in a $3.6 billion acquisition by Guinness last spring. Mr. Seelig, 41 years old, led the team that advised Guinness in its bid for the Distillers Company. He reportedly earned almost $300,000 a year.