The Nasdaq Composite Index fell the most in almost a month Wednesday, dragged down by losses in Apple Inc. after a competitor introduced new smartphones and the company faced criticism for the theft of celebrity photos.

Apple, the world’s most valuable company, sank 4.2 percent for its biggest decline since January. Delta Air Lines Inc. lost 5.2 percent after it lowered forecasts for some third-quarter targets. PulteGroup Inc. fell 3.8 percent as homebuilders tumbled.

The Nasdaq Composite lost 0.6 percent, the most since Aug. 5. Apple has the biggest weighting in the gauge at 8.7 percent.

The Standard & Poor’s 500 Index slid 0.1 percent to 2,000.72, while the Dow Jones industrial average climbed 10.72 points, or 0.1 percent, to 17,078.28. About 5.4 billion shares changed hands on U.S. exchanges Wednesday, 3.1 percent below the three-month average.

“Apple stock’s had a pretty strong move in the last several months,” said Michael James, a Los Angeles-based managing director of equity trading at Wedbush Securities Inc., in an interview. “A lot of positives from the iPhone launch are built into the stock price at these levels. People are merely taking profits.”

Apple had rallied in 15 of the previous 17 sessions, adding 9.3 percent since Aug. 7 to reach a record close of $103.30 Tuesday.

Samsung Electronics Co. unveiled a pair of Galaxy Note smartphones Wednesday, as the No. 1 seller tried to fend off Apple’s push into large-screen devices.

Apple said Tuesday that a spate of nude photos from actresses including Jennifer Lawrence that were recently posted online were individually stolen from Apple accounts. The theft, which prompted scrutiny from the U.S. Federal Bureau of Investigation, threatened to mar an Apple event Tuesday, where the company is set to unveil new iPhones, a wearable device and a mobile-payments system, people with knowledge of the matter have said.

Apple led an S&P 500 index of technology stocks lower by 0.7 percent, the most among 10 main groups in the broader gauge. The Nasdaq 100 Index of large technology companies dropped 0.6 percent, the most since Aug. 5.

The S&P 500 earlier climbed to an intraday record on reports that Russia President Vladimir Putin outlined a peace plan for Ukraine after agreeing with his counterpart Petro Poroshenko on steps toward a cease-fire in the conflict that has raged for more than five months.

The Fed’s Beige Book, a survey based on reports from the 12 regional banks, showed the U.S. economy continued to expand during the summer, with none of the country’s regions experiencing a shift in the pace of growth. Policy makers next meet Sept. 16-17.

Delta plunged 5.2 percent to $38.82, the steepest slide in more than two months. In a presentation to analysts at a Cowen & Co. conference, Delta said revenue for each seat flown a mile will increase 2 percent to 3 percent in the third quarter, down from a previous forecast of 2 percent to 4 percent.

An S&P index of homebuilders slid 3 percent as all 11 members declined. Toll Brothers Inc., the largest U.S. luxury-home builder, fell 4.7 percent after it said orders for new homes dropped, and it lowered its forecast for sales this year.

PulteGroup Inc. slid 3.8 percent, while Lennar Corp. and D.R. Horton Inc. dropped at least 2.2 percent.