Rakuten Inc. reported an unexpected quarterly loss Thursday, hit by the depressed value of its investment in ride-hailing firm Lyft Inc. and heavy spending on a new wireless service.

The company said it booked a ¥1.8 billion operating loss in the April-June quarter compared with a ¥61.6 billion profit in the same period a year earlier. The market had expected a ¥5.2 billion profit, according to the average of five analysts compiled by Refinitiv.

Rakuten, whose billionaire founder and Chief Executive Hiroshi Mikitani has a seat on Lyft's board, recorded a ¥28.4 billion unrealized loss on its stake in the ride-hailing firm for April-June, as it had warned in July. It recorded a ¥110 billion gain in the previous quarter.

The results come a day after SoftBank Group Corp. posted an unrealized loss on its stake in Lyft rival Uber Technologies Inc. for the April-June quarter. The two money-losing firms are locked in a cash-burning battle for dominance in the U.S. market.

Rakuten cited an operating loss in its mobile services business as it steps up investment in a new wireless service that is due to launch in October. The move will make it Japan's No. 4 mobile carrier.