A report in yesterday's Business section incorrectly stated the percentage decline in Giant Food's third-quarter earnings from the third quarter of 1983. The decline was 3.4 percent.

Giant Food Inc. reported profits of $8.5 million (57 cents a share) for its third quarter, a 34 percent decrease from earnings of $8.8 million (60 cents) in the same period last year.

The Washington-based food and drug supermarket chain reported third-quarter revenue was $448 million, compared with $439 million last year. For the first nine months of its fiscal year, Giant reported net income of $27.5 million ($1.86) on revenue of $1.4 billion, up 7 percent from profits of $25.8 million ($1.76) on sales of $1.3 billion the year before.

Giant said the third-quarter results match the company's expectations following the launching of a discount pricing program in its 74 drug stores in June. The drug program, however, is expected to win new customers and help long-range profit levels, the company said.

In another profit report, D.C.-based Computer Network Corp. (Comnet) reported a loss of $541,000 (28 cents a share) for its second quarter ended Sept. 30, compared with a loss of $848,000 (45 cents) in the same period of 1983. Second-quarter revenue was $4.3 million, unchanged from the year before. The company said "a substantial portion" of the losses represented unusual, or one-time, expenses.

Comnet said it lost $1 million (56 cents) in the first six months of its fiscal year on revenue of $6.1 million, down from a loss of $971,000 (52 cents) on sales of $8 million in the first half of last year.