The ride-hailing giant Uber Technologies is not a public company, but every three months, shareholders get on a conference call to hear details on its business performance from its head of finance, Gautam Gupta.

On Friday, Gupta told investors that Uber’s losses mounted in the second quarter. Even in the U.S., where Uber had turned a profit during its first quarter, the company was once again losing money.

In the first quarter of this year, Uber lost about $520 million before interest, taxes, depreciation and amortization, according to people familiar with the matter. In the second quarter the losses significantly exceeded $750 million. That means Uber’s losses in the first half of 2016 totaled at least $1.27 billion.

Subsidies for Uber’s drivers are responsible for the majority of the losses globally, Gupta told investors. An Uber spokesman declined to comment.

“You won’t find too many technology companies that could lose this much money, this quickly,” said Aswath Damodaran, a business professor at New York University skeptical of Uber’s astronomical valuation. “For a private business to raise as much capital as Uber has been able to is unprecedented.”

Bookings grew tremendously from the first quarter of this year to the second, from above $3.8 billion to more than $5 billion.