(July 17): Wall Street ended lower on Friday, weighed down by declines in Amazon, Apple and other heavyweight technology stocks, while investors worried about a rise in coronavirus cases tied to the highly contagious Delta variant.

On Thursday, Los Angeles County said it would reimpose its mask mandate this weekend. On Friday, public health officials said U.S. coronavirus cases were up 70% over the previous week, with deaths up 26%.

Cruise lines Carnival Corp and Norwegian Cruise Line both fell about 5%.

"COVID is starting to affect the market, ironically, for the first time since last summer, when the reopening trade began," said Jake Dollarhide, chief executive officer of Longbow Asset Management in Tulsa, Oklahoma.

Amazon and Apple fell more than 1%. Nvidia lost 4.2%, and the three companies contributed more than any others to the S&P 500 and Nasdaq's declines. The S&P 500 technology sector index lost almost 1%, dipping for a second session after hitting a record on Wednesday.

The utilities index rallied 1%, while the real estate index edged up 0.1% and touched an intraday record high.

This week, investors have balanced worries about a recent inflation spike with reassurances from Fed Chair Jerome Powell that the surge in prices is temporary.

Second-quarter earnings season picks up next week, with reports from companies including Netflix, Johnson & Johnson, Verizon Communications, AT&T and Intel.

Analysts on average expect 72% growth in earnings per share for S&P 500 companies, according to IBES estimate data from Refinitiv.

With the S&P 500 up about 15% so far this year, investors will look for strong company forecasts to justify sky-high valuations.

"It's been hard for the market to gain here from these already elevated prices," said Rick Meckler, partner at Cherry Lane Investments in New Vernon, New Jersey.

The S&P 500 energy sector index sank nearly 3% and ended the week 8% lower, with investors worried about expectations for more supply and a rise in coronavirus cases that raised demand concerns.

Data from the Commerce Department showed retail sales rebounded 0.6% last month as spending is shifting back to services, bolstering expectations that economic growth accelerated in the second quarter.

The Dow Jones Industrial Average fell 0.86% to end at 34,687.85 points, while the S&P 500 lost 0.75% to 4,327.16.

The Nasdaq Composite dropped 0.8% to 14,427.24.

For the week, the S&P 500 fell about 1%, the Dow lost 0.5% and the Nasdaq shed 1.9%, their fist weekly declines in four weeks.

Moderna Inc jumped 10.3% to a record high after S&P Dow Jones Indices said the drugmaker will join the S&P 500 index as of the start of trading on July 21, replacing Alexion Pharmaceuticals.

Cintas Corp surged 4.6% after brokerages raised price targets on the business service provider's stock following its fourth-quarter results.

Didi Global Inc fell 3.2% after China sent state officials from at least seven departments to the ride-hailing giant for a cybersecurity review.

Declining issues outnumbered advancing ones on the NYSE by a 2.42-to-1 ratio; on Nasdaq, a 2.21-to-1 ratio favored decliners.

The S&P 500 posted 48 new 52-week highs and no new lows; the Nasdaq Composite recorded 46 new highs and 124 new lows.

Volume on U.S. exchanges was 9.3 billion shares, compared with the 10.3 billion average for the full session over the last 20 trading days.