A new report estimates that the company led by Elon Musk accounted for just under half of all battery-powered vehicles sold in the second quarter of the year.

Tesla’s once-commanding share of the market for electric vehicles in the United States slipped below 50 percent in the second quarter of the year even as sales of battery-powered cars surged to a record, according to new estimates published Tuesday by a research firm.

Tesla accounted for 49.7 percent of electric vehicles sales from April through June, down from 59.3 percent a year earlier as the company led by Elon Musk lost ground to General Motors, Ford Motor, Hyundai and Kia, the research firm, Cox Automotive said. It was the first time the company’s market share fell below 50 percent in a quarter, according to Cox. The firm, a leading auto industry researcher, estimates market share based on registrations, company reports and other data.

The numbers are the latest sign that Tesla is losing its dominance in a market it in effect created in 2012 when it introduced the Model S sedan. Before that car, very few electric vehicles were sold in the United States.

Overall, U.S. electric vehicle sales climbed 11.3 percent from a year earlier, suggesting that consumer demand for the technology remains healthy even if sales are no longer growing at more than 40 percent a year as they were last year. Americans bought or leased more than 330,000 electric cars and light trucks during the quarter, accounting for 8 percent of all new cars sold or leased in the three-month period. A year earlier, electric vehicles accounted for 7.2 percent of the market, Cox said.

A few years ago Tesla didn’t have many competitors, and pretty much no other company could match its cars’ driving range on a full charge or acceleration. But established carmakers have been introducing electric vehicles that can travel 300 miles or more, equaling and sometimes exceeding the capabilities of Tesla’s cars.

There are well over 100 electric models available in the United States, according to a separate report published Tuesday by the Alliance for Automotive Innovation, an industry group. Prices have fallen as the supply and variety of models have increased, making it possible for more people to afford one.

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