SoftBank Group Shares Tumble on OpenAI Competition Worries

SoftBank Group shares tumbled on Tuesday, hitting a 2 1/2-month low on worries that the latest Gemini artificial intelligence model from Alphabet may intensify competition for OpenAI — the Japanese conglomerate’s key investment.

The stock sank as much as 11% on Tuesday, following a 10.9% dive in the previous session before Japan’s long weekend. The sharp back-to-back declines stand out even for SoftBank Group, whose shares are highly volatile.