NEW YORK, JULY 9 -- Stock prices finished mixed today in a session marked by profit taking in many of the blue chips.

The Dow Jones average of 30 industrials, after reaching a record high on Wednesday, dropped back 12.76 to 2451.21. Volume on the New York Stock Exchange came to 195.40 million shares, against 207.46 million in the previous session.

One apparent drag on the market was a rise in open-market interest rates, which pushed prices of long-term government bonds down about $5 on average for each $1,000 in face value.

Trading volume has increased this week as the market continued the rally that began in late May. Analysts have generally been hoping for a pickup in activity to suggest that investors are buying with confidence and conviction.

But the market's "breadth" -- the number of stocks advancing -- remained unimpressive today. Brokers said that prompted some traders to remain skeptical about the durability of the rally, and to cash in some of their gains.

Golden Nugget was actively traded, up 1 5/8 at 13 1/2. Financier Donald Trump said he holds a 4.9 percent stake in the company, and indicated that he might try to gain control of it.

Southland Corp. climbed 1 1/2 to 78. Some traders apparently are speculating that the company, which has agreed to be bought out by its founding family for $77 a share, might attract a higher bidder.

Losers among the blue chips included American Express, down 1/4 at 33 3/8; General Electric, down 7/8 at 55 3/4; Philip Morris, down 2 1/8 at 91; International Business Machines, down 1/2 at 166 1/4, and RJR Nabisco, down 1 at 53 5/8.

Airborne Freight fell 4 1/2 to 28 1/4, posting one of the day's biggest percentage declines. Late Wednesday the company estimated lower earnings for the second quarter.

Conrail led the active list, up 3/8 at 33 1/4. The stock, which has been added to Standard & Poor's 500-stock composite index, apparently benefited from buying by index funds that seek to duplicate the performance of the 500.

Advancing issues outnumbered declines by about 9 to 8 on the NYSE, with 819 up, 757 down and 425 unchanged. The exchange's composite index slipped 0.27 to 173.15.

Nationwide turnover in NYSE-listed issues, including trades in those stocks on regional exchanges and in the over-the-counter market, totaled 227.26 million shares.

Standard & Poor's index of 400 industrials fell 0.89 to 358.91, and the S&P 500 was down 0.77 at 307.52.

The Nasdaq composite index gained 0.65 to 425.58. At the American Stock Exchange, the market value index hit a new high for the third straight day, closing at 346.79, up 0.22.