Stocks extended their decline by late afternoon Thursday as crude oil retreated from recent highs. 

The S&P 500 was down 0.63%, the Dow Jones Industrial Average fell 0.7%, and the Nasdaq slid 0.23%.

Crude oil prices pulled back from Wednesday's highs after rallying to their best settlement in five months. Oil had shot higher after weekly inventory was better than most expected. U.S. crude inventories added 2.1 million barrels last week, according to the Energy Information Administration

West Texas Intermediate crude oil for June delivery closed 2.3% lower to $43.18 a barrel after two sessions of robust gains. 

Verizon (VZ - Get Report)  dragged on the telecom sector after falling more than 4%. The telecom giant posted earnings of $1.06 a share in its first quarter, 4 cents higher than a year earlier but as analysts had expected. Revenue of $32.2 billion came in slightly short of forecasts. The iShares Dow Jones U.S. Telecom ETF (IYZ - Get Report) fell 1.7%.   

Just over one-tenth of the S&P 500 has reported first-quarter earnings so far this season. Of those that have reported, 76% have beat earnings estimates, while 17% have missed. The blended growth estimate for the quarter is expected to fall 7.5%, the fourth quarter in decline.

Biogen (BIIB - Get Report) was more than 4% higher after a mixed first quarter. The drugmaker reported earnings of $4.79 a share, breezing past estimates of $4.44. Revenue of $2.73 billion was higher than a year earlier but slightly below expectations.

Biogen is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before he buys or sells BIIB? Learn more now.

American Express (AXP - Get Report) added 0.9% following a better-than-expected quarter. The credit-card company earned $1.45 a share in its recent quarter, a 6% drop from a year earlier, but above analysts' estimates of $1.36 a share. Revenue of $8.06 billion was in line with forecasts.

General Motors (GM - Get Report) jumped 1% after doubling earnings in its first quarter. Profit of $1.24 a share came in far higher than 56 cents a share a year earlier. On an adjusted basis, earnings of $1.26 a share blew past forecasts of 99 cents.

Yum! Brands (YUM - Get Report) , the parent company of fast-food brands Pizza Hut, KFC and Taco Bell, reported first-quarter earnings of 95 cents a share, above estimates of 83 cents, as growth in China recovered. KFC China reported same-store sales growth of 12%, recovering from a challenging 2015. Shares fell 0.9%.

United Airlines (UAL - Get Report) reported first-quarter earnings above expectations, though guidance for its current-quarter performance disappointed. The Chicago-based airline said it expects unit revenue to fall 6.5% to 8.5% from a year earlier on a weaker April and a stronger U.S. dollar. Shares fell 10%.

Qualcomm (QCOM - Get Report) fell more than 1% despite a double-digit jump in quarterly profit. However, revenue was under pressure as chip shipments fell 19% and equipment and services revenue tumbled 25%. Overall revenue fell 19% to $5.6 billion.

Stanley Black & Decker (SWK - Get Report) shares added 3.5% after the tool maker boosted earnings and revenue in its recent quarter, while increasing its full-year outlook. The company expects full-year earnings of at least $6.20 a share, up from a low-end range of $6. Management said it has seen stronger organic growth in its tools and storage business.

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Southwest Airlines (LUV - Get Report) rose as quarterly profit jumped 13% on cheaper fuel costs. Fuel and oil expenses fell 2.9% over the quarter with the average cost of fuel falling to $1.78 a gallon from $2 a year earlier.

SunEdison (SUNE) was slightly lower after filing for Chapter 11 bankruptcy protection. Investors had expected the move for weeks on concerns over its liquidity position. The solar energy company secured $300 million in debtor-in-possession financing while it completes restructuring. Shares have fallen 94% since the beginning of the year.

European stocks were lower on Thursday after the European Central Bank kept rates steady for another month. The central bank held its deposit rate at negative 0.4% and its main refinancing rate at 0%. The decision to hold rates as is was expected.

"Based on our regular economic and monetary analyses, we decided to keep the key ECB interest rates unchanged," ECB President Mario Draghi said in prepared remarks. "We continue to expect them to remain at present or lower levels for an extended period of time, and well past the horizon of our net asset purchases."

The number of new claims for unemployment benefits in the U.S. hit their lowest level since November 1973 in the past week. New jobless claims fell 6,000 to 247,000, according to the Labor Department.

Business conditions in the Philadelphia region took an unexpected turn south. The business outlook fell to negative 1.6 compared to an expected positive 8.9 reading, according to the Federal Reserve Bank of Philadelphia.

"Even though the drop in the headline Philly Fed index pushed it only marginally below the zero mark, the weakness in the details of the report offers a far more sobering outlook for the U.S. manufacturing sector," said Millan Mulraine, deputy chief U.S. macro strategist at TD Securities.