Stocks Post Moderate Gains; Dow Rises 6.75

The stock market staged a moderate advance in quiet trading Thursday, extending its on-again-off-again bid to rally from its July selloff.

The Dow Jones average of 30 industrials rose 6.75 to 1,786.28, bringing its gain since the start of the week to 22.64 points.

Volume on the New York Stock Exchange came to 122.44 million shares, against 127.51 million on Wednesday.

Analysts said hopes were apparently increasing among traders that the market could gather strength after the completion of the Treasury’s quarterly financing.

The $28-billion sale concluded Thursday with the auction of $9 billion in 30-year bonds at an average yield of 7.63%. Prices of existing government bonds rose in afternoon trading pending the results of that offering.

However, brokers also said the market’s initial upbeat response had faded to the Organization of Petroleum Exporting Countries’ agreement on temporary production cutbacks.

Many analysts said it remained to be seen whether OPEC had made any significant progress in its efforts to shore up world oil prices.

The big-name energy issues generally recorded small losses. Exxon dropped 3/8 to 62 3/4, Mobil 1/8 to 32 3/4 and Amoco 5/8 to 62.

Retailing issues, by contrast, were mostly higher as leading companies in the industry reported improved sales for July. Zayre, which posted a 31.1% sales increase, rose 1 5/8 to 28 1/2 in active trading.

Elsewhere in the group, Sears gained 3/4 to 42 3/8, K mart 3/4 to 52 and Federated Department Stores 1 3/8 to 79.

Blue chips that contributed to the Dow Jones industrial average’s rise included International Business Machines, up 1 at 131; American Can, up 3 at 85 3/4, and McDonald’s, up 1 3/8 at 62.

Owens-Corning Fiberglas led the active list and rose 2 1/2 to 77. The company said it was studying overtures from Wickes Cos. to discuss a $70-a-share acquisition of Owens-Corning by Wickes.

Wickes shares, traded on the American Stock Exchange, dropped to 5 1/2.