The stock market turned downward today, ending a run of five consecutive gains, but bond prices rallied as traders concluded the Treasury's borrowings next week will not be too large.

The stock market decline was ascribed in part to reports some members of the Organization of Petroleum Exporting Countries might be planning price increases.

The Dow Jones average of 30 industrials, which had claimed nearly 58 points since early last week, dropped 8.27 to 808.79.

New York Stock Exchange volume increased slightly to 32.48 million shares from 30.85 million yesterday.

The three most active NYSE issues are all oils -- Exxon, down 1/8 at 60 5/8; Texaco, off 5/8 at 37 3/4; adn Mobil, down 5/8 at 72 1/8.

Standard Oil of California was down 1 at 69 3/4; Indiana Standard lost 7/8 to 101 1/4, and Atlantic Richfield dropped 2 1/2 to 89 1/4.

Among leading defense issues, Boeing lost 1 to 35 1/2 in active trading; McDonnell Douglas 1 to 28 5/8; and Lockheed 1 to 31 3/8.

Analysts said some traders sold on the belief the market's recent rally could not go much further in the face of continuing evidence of an economic slowdown.

Precious metals stocks declined in early trading, but recovered to finish mixed. ASA was up 1/4 t 41 7/8 and Homestake Mining added 1/4 to 46, while Dome Mines dropped 1 to 60 1/2.

The daily tally on the NYSE showed about four losers for every three stocks that gained ground. The exchange's composite index dropped .42 to 59.94.

Nationwide turnover in NYSE-listed issues, including trades in those stocks on regional exchanges and, in the over-the-counter market, came to 37.47 million shares.

Standard & Poor's index of 400 industrials gave up 1.02 to 118.52, and S&P's 500-stock composite index was down .83 to 105.46.

On the bond market, corporate bond prices rose sharply in active trading, with industrials up 1 1/2 t 2 points and utilities up 1 to 1 1/2 points.

Government issues were up 15-32 in intermediate and 22-32 in long maturities. Short-term governments advanced 8-32, according to the investment banking firm of Salomon Brothers.

The Treasury announced after trading ended yesterday it will raise $3.5 billion in new funds through the sale of three bond and note issues next week. That was viewed as being within market expectations by many traders. On the same day, the government reported a large drop in the leading economic indicators, providing more evidence of a recession.

Short-term interest rates, which had been declining rapidly, showed little change today.

Three-month Treasury bills were up 10 basis points to 10.30 percent; six-month bills fell 10 basis points to 10.32 percent; and one-year bills declined 8 basis points to 10.08 percent.