Fluence Energy narrowed its loss in the second quarter and said it had signed supply agreements with two artificial-intelligence hyperscalers.

The energy storage company on Wednesday said its backlog has reached a record level and orders have accelerated in recent months.

"Our customer expansion strategy is gaining momentum: we have signed master supply agreements with two hyperscalers and expect to convert our first order soon," Chief Executive Julian Nebreda said. The company didn't identify the customers.

Shares surged 35% to $18.33 in after-hours trading Wednesday. The stock closed up 6.9% at $13.56, and is down 31% this year.

Fluence reported a loss of $20.9 million, or 16 cents a share, compared with a loss of $31 million, or 24 cents a share, a year earlier.

Revenue rose to $464.9 million, up from $431.6 million a year prior.

Analysts were expecting a loss of 16 cents a share and revenue of $614.9 million.

The company reaffirmed its full-year guidance.