SoftBank Group’s market value halved from its peak in June, as higher borrowing costs fuel investor concerns over the sustainability of its massive investments in artificial intelligence.

Shares of the Tokyo-based company fell 6.9% on Thursday, taking their drop from an all-time high struck on June 2 to 50%, with earnings from U.S. megacaps failing to ease the angst. After briefly overtaking Toyota as Japan’s biggest company four months ago, its market capitalization is now about ¥24.7 trillion ($157 billion), smaller than that of Hitachi and Recruit.

Global concerns over AI spending had accelerated after U.S.-based cloud-computing provider CoreWeave’s bonds fell to levels associated with distress, exposing financing risks across the industry.

“SoftBank’s vulnerability stands out as investors increasingly scrutinize the financial health of AI-related companies, given the group’s highly leveraged financial structure and growing borrowing costs,” said Kazuyuki Muramatsu, head of investment management at…