Japan's SoftBank Group booked a surprise $2.4 billion quarterly loss on Wednesday, hit by a decline in the value of e-commerce platform Coupang and other tech companies held by its Vision Fund investment arm.

SoftBank Group Corp. tumbled to a loss in the December quarter, weighed down by a drop in the value of the Vision Fund’s public holdings, just as Masayoshi Son campaigns to raise $500 billion for the Stargate artificial-intelligence project.

The tech investment company reported a quarterly loss, partly due to the weakness in its technology funds business, as it geared up for the Stargate project.