By Riva Gold and Aaron Kuriloff 

U.S. stocks fell Thursday, led by declines in the telecommunications and utilities shares.

Those two sectors, considered relatively stable and safe, have risen the most in the S&P 500 over the past 12 months. Their declines Thursday helped push the Dow industrials below 18000, after the index this week closed above the milestone for the first time since July.

Telecommunications stocks in the S&P 500 fell sharply. Shares of Verizon Communications dropped 3.3% after the company reported that revenue rose less than analysts had anticipated and said that earnings may plateau in 2016.

Travelers Cos. fell the most in the Dow industrials. Shares declined 6% after the insurer reported a first-quarter profit decline of 17%, citing losses from wind and hail storms in Texas.

United Continental shares dropped 10% after reporting late Wednesday that first-quarter net income dropped 38% from a year earlier.

The Dow Jones Industrial Average fell 0.6%. The S&P 500 declined 0.5% and the Nasdaq Composite Index fell less than 0.1%.

The declines came as the number of U.S. workers who applied for unemployment benefits fell to the lowest level in 43 years, a sign of ongoing strength in the labor market. Initial claims for jobless benefits fell by 6,000 to a seasonally-adjusted 247,000 in the week ended April 16, the Labor Department said.

"If the growth outlook's improving, and we're not going into recession, the very expensive insurance premium that stable stocks provide for the market becomes less valuable," said Peter Stournaras, portfolio manager of the BlackRock Large Cap Series Funds.

The Stoxx Europe 600 fell 0.3% after the European Central Bank kept rates on hold, as expected. The euro fell less than 0.1% against the dollar to $1.1301.

ECB President Mario Draghi said interest rates will remain at present or lower levels for an extended period, keeping the possibility of further interest-rate cuts on the table. He also noted that inflation could turn negative in the coming months before picking up later this year.

Mr. Draghi offered little new information to investors in his news conference Thursday, said Philippe Gijsels, chief strategist at BNP Paribas Fortis.

"He was trying to convince the market he'll do whatever it takes and recent measures are working...but the market reaction is not extremely positive," he said. Still, investors may take heart in details on the bank's corporate bond purchases. "I think he has a clear ambition to go fairly strongly into the corporate bond market."

The Bank of Japan also meets next week, and many investors expect the bank to signal future interest-rate cuts. Former Bank of Japan deputy Governor Kazumasa Iwata on Thursday said the central bank would need to lower its interest rate to as much as minus 1% from negative 0.1% to tackle deflation.

But the yen has continued to rise sharply since the Bank of Japan adopted negative interest rates, while shares of banks and exporters have come under pressure.

On Thursday, stocks in Japan hit a two-month high and ended up 2.7% as a weaker yen alleviated pressure on shares of exporters. Still, the Nikkei Stock Average remains lower than it was before the bank announced its stimulus measures.

Shares in Hong Kong and Australia also gained, though the Shanghai Composite Index ended lower in volatile trading. That came despite the People's Bank of China's injection of 220 billion yuan into the financial system Thursday through the purchase of short-term loans known as reverse repurchase agreements.

U.S. crude prices fell 2.3% to $43.18 Thursday. Stabilizing oil prices have helped boost stocks during a two-month rebound that has left the S&P 500 and Dow industrials both near record closes hit in May 2015.

"It's been an incredible rally," said Joe Tanious, strategist at Bessemer Trust. But with relatively full valuations in the U.S. and lackluster corporate earnings, "it's very difficult to identify drivers that can move the market a heck of a lot higher from here," he said.

Write to Aaron Kuriloff at aaron.kuriloff@wsj.com and Riva Gold at riva.gold@wsj.com

(END) Dow Jones Newswires

April 21, 2016 18:23 ET (22:23 GMT)