The Dow Jones industrial average closed up 1.11 at 5,712.38.
Advancers led decliners by 1,303 to 1,028 on the New York Stock Exchange. NYSE volume totaled 296.38 million shares vs. 306.36 million in the previous session.
Among broader markets, the NYSE composite fell 0.36 to 356.79, and the S&P 500 fell 1.59 to 664.81. The Nasdaq rose 4.30 to 1,153.32, and the Amex market value index advanced 1.34 to 563.39.
The Dow gained more than 10 points in the morning exclusively on the strength of IBM Corp. Salomon Brothers upgraded the computer maker's stock, noting that the quarter ended June 30 saw its "best revenue acceleration in the past five quarters." Big Blue's stock stood at $114.62-1/2, up $2.87-1/2, at closing on the New York Stock Exchange.
But stock prices deteriorated in early afternoon as investors worried about $12.5 billion in five-year notes auctioned by the Treasury.
The yield on the 5-year note came in at 6.568 percent, the lowest level since May. But bond traders said Wall Street firms that took down the notes might have trouble reselling them, because so many participants are absent from the market and on vacation.
That nervousness in the bond market spilled over into stocks. "Our audience is so limited that any move is going to be exacerbated," said Bill Allyn, director of listed equity trading at Jefferies & Co. in Short Hills, N.J.