SAN FRANCISCO (AP) — Tesla suffered a loss of $408 million during its latest quarter as the company continues to struggle to prove it can make money while producing electric cars at prices that a mass market can afford.

The setback announced Wednesday had already been telegraphed by Tesla CEO Elon Musk, but it still underscored an ongoing challenge that helps explains why the company's shares have plunged by more than 20% so far this year while the Standard & Poor's 500 index has surged by 20%.

On the upside, Tesla's revenue climbed 47% from the same time last year to $5.2 billion. The company also generated $614 million in cash during the quarter.

But the loss was larger than analysts projected, and Tesla's stock dropped another 11% to $236 in extended trading.