SoftBank Group booked a ¥789 billion ($5.2 billion) quarterly loss on Thursday, its fourth straight quarter in the red, as the Japanese tech giant wrote down the value of tech investments and took a hit from the bankruptcy of the once high-flying WeWork.

The results underscore the volatility and risk inherent in founder Masayoshi Son's strategy of betting big on often risky startups. The loss was also a reminder of how even the likes of SoftBank — famous for a focus on cutting-edge technology — can be brought to earth by workaday problems like currency rates.

The Japanese conglomerate said it was squeezed by weakness in the yen that drove up costs on its dollar-denominated debt.