By Leslie Josephs 

Big oil companies pulled the Dow Jones Industrial Average lower on Friday, on disappointing earnings reports and a sign of increased U.S. oil drilling despite a renewed slump in crude prices.

The Dow Jones Industrial Average shed 56.12 points, or 0.3%, on the day to 17689.86. The index was down from an intraday high of 17783.5. The S&P 500 reversed from modest gains earlier in the session to fall 4.7 points 0.2% to 2103.84. The Nasdaq Composite Index fell less than 0.1%, or 0.5 points to 5128.28.

On the other side of the Atlantic, the Stoxx Europe 600 rose less than 0.1% to 396.37.

Shares of large U.S. oil companies, already pressured by downbeat earnings reports, fell after oil-field services firm Baker Hughes said on Friday afternoon that the number of active U.S. oil rigs rose by five this week to 664, the second consecutive weekly increase.

Oil futures prices fell after the data were released, with Nymex crude settling at $47.12 a barrel, down 2.9%, or $1.40.

Exxon Mobil Corp., the biggest U.S. oil company earlier on Friday reported a 52% decline in profit for its second quarter and its stock price fell 4.6% to $79.21. Chevron shares were down 4.9% at $88.48 on Friday, after the company reported $2.6 billion in quarterly charges tied to lower oil prices.

Together the two companies' share-price drop shaved about 56 points off the Dow. "That should not surprise anyone," Randy Frederick, managing director of trading and derivatives at Charles Schwab, said of the oil companies' results.

Still, the Dow Industrials eked out a 0.4% gain in July, the largest since May. The S&P 500 rose about 2% in the month, the biggest monthly percentage gain since February.

Friday's losses were somewhat muted by a report that showed paltry growth in U.S. wages, which cast some doubt over whether the Federal Reserve would raise interest rates in the coming months.

The U.S. employment-cost index, a measure of workers' wages and benefits, rose a seasonally adjusted 0.2% in the second quarter from the first quarter, the Labor Department reported. The gains marked the smallest quarterly rise since record-keeping began in 1982, and fell below economists' expectations of a 0.6% increase.

"I think what the markets are reading is that once again this another one in the column for "no" [for a Fed rate rise] in September," said Jeffrey Yu, head of single-stock derivatives trading at UBS Group AG.

Even if the Fed were to raise rates by a quarter percentage point, it wouldn't likely encourage investors to sell stocks and pile into other asset classes like bonds, said Gordon Charlop, managing director at Rosenblatt Securities. "What does a quarter [percentage] point do? Does it mean I'm going to sell all my equities? I don't think so," Mr. Charlop said. "It's like jumping off a snake's belly."

Shares of Coca-Cola Enterprises Inc. rallied 12.4% at $51.08 following news of merger talks with Coke bottlers Coca-Cola Iberian Partners and Germany's Coca-Cola Erfrischungsgetranke AG.

Shares of Hanesbrands Inc. dropped 9.11 % to $31.03 after the apparel maker posted s econd-quarter sales below analyst estimates.

The dollar weakened 0.5% against the common currency, as one euro bought $1.0981 in late-afternoon trade.

Gold futures posted their steepest monthly decline since June 2013, after investors slashed gold holdings in anticipation of higher U.S. interest rates. The most actively traded contract, for December delivery, settled up $6.40, or 0.6%, at $1,095.10 a troy ounce on the Comex division of the New York Mercantile Exchange.

Write to Leslie Josephs at leslie.josephs@wsj.com