SoftBank shares have plunged approximately 50% from their record high set on June 2, with market capitalization falling to roughly $157 billion. The decline reflects rising financing costs and growing investor skepticism about the sustainability of the company's large-scale AI investments. Just four months ago, SoftBank briefly surpassed Toyota as Japan's most valuable publicly traded company. Credit default swap (CDS) prices for SoftBank surged to their highest level in nearly four years this week, amplifying concerns about its debt-dependent strategy for building AI infrastructure. The broader market is increasingly scrutinizing financing risks across the AI sector, with SoftBank's heavy reliance on borrowing to fund expansion drawing particular attention.