TOKYO—Japanese technological know-how investor SoftBank Group Corp. on Monday documented a loss of much more than $23 billion in the three months to June right after its Vision Fund investments experienced from the international selloff in technology shares.

SoftBank described a web reduction of ¥3.16 trillion, equal to $23.4 billion, for the quarter ended June 30. That compares with a net decline of ¥2.1 trillion in the January-March quarter. For SoftBank’s complete fiscal year finished March 31, it noted a reduction of ¥1.71 trillion, a report.