BUSINESS HIGHLIGHTS

GM cuts car production plans Detroit General Motors, bothered by swollen inventories for much of the year, has reportedly cut fourth-quarter production plans by 33,000 cars, which will put its scheduled output for the period about 100,000 below a year ago.

Ward's Automotive Reports, an authoritative weekly that tracks US auto industry production, said Ford Motor Company and Chrysler Corporation each plan higher production through December period. Quaker Oats gains pet food New York

Quaker Oats Company of Mount Airy, N.C., and Anderson Clayton & Co. of Houston have agreed to an $800 million merger that will make Quaker the No. 2 pet food company in the country.

Quaker, which had purchased 2.87 million Anderson Clayton shares on Thursday, said Sunday it had signed a definitive agreement to buy the remaining 9.3 million shares.

The agreement would end Quaker's bidding war against Ralston Purina Company of St. Louis, the No. 1 pet food company, for Anderson Clayton. Renault sees profit in '87 Paris

Renault expects to return to profitability at the end of 1987 after further reducing losses this year, says chairman Georges Besse.

Mr. Besse told Le Monde Renault would cut its consolidated net loss to between around 6 billion francs ($760 million and $900 million) this year, from 10.9 billion francs ($1.6 billion) last year.

Besse stressed that recent losses at Renault's American Motors Corporation subsidiary were far from being the main cause of losses at the Renault group. He said Renault should not become a strictly French group. CBS inside trades suspected New York

The Securities and Exchange Commission is investigating the possibility that there was widespread insider trading in CBS stock and stock options in connection with takeover efforts by Denver oilman Marvin Davis, according to published reports.

The Wall Street Journal reported Monday that Robert Ackermann, chief of market surveillance at the Chicago Board Options Exchange, said the inquiry was prompted by suspiciously heavy trading during four periods within the past year.