The electric-car maker Tesla faces challenges in introducing its first mass-market vehicle, but the company’s chief executive, Elon Musk, sought to reassure investors on Wednesday that the company was up to the task.

Tesla may experience some fluctuations in production rates, Mr. Musk said, but “people should have zero concerns” about the company’s ability to increase production of the new offering, the Model 3.

Mr. Musk’s comments came on a conference call after Tesla announced its second-quarter earnings. Despite the company experiencing a widening loss as it continued to invest in factories to accommodate the Model 3, investors found plenty to like in its prospects. Tesla shares were up more than 7 percent in extended trading.

Tesla said it lost $401.4 million in the quarter that ended June 30, compared with a loss of $293.2 million in the same period in 2016.