SoftBank Group Corp. has reported a record profit in its Vision Fund as a surging stock market lifted the value of its portfolio companies, but founder Masayoshi Son wiped out a significant chunk of those gains with his controversial trading in derivatives.

The Vision Fund on Monday reported a ¥844.1 billion ($8 billion) profit in the December quarter, surpassing record numbers set just a quarter earlier. A global rally in technology shares has boosted the value of SoftBank’s stakes in publicly traded firms like Uber Technologies Inc. and paved the way for initial public offerings from the likes of DoorDash Inc.

Those gains, which had been widely expected, were offset by fallout from Son’s decision last year to start dabbling in trading stocks and options. SoftBank posted a ¥285.3 billion derivatives loss in the period. That led to an overall loss in the asset management arm of ¥113.5 billion, up from ¥85.2 billion in the previous three-month period.