SoftBank’s AI-Driven Surge Reshapes Japan’s Equity Landscape

SoftBank Group Corp. has become an inescapable force in Japan's equity markets, with its 146% rally this year now commanding influence rivaling Toyota Motor Corp. on the Topix index. The tech investment giant's $110 billion market cap expansion since March alone accounts for nearly 10% of the benchmark's total growth—a gravitational pull that's forcing institutional investors to reconsider longstanding skepticism.

"Structural pressures are creating a no-win scenario for fund managers," said Yoshiki Nagata of enTorch Capital Partners. Benchmark-tracking portfolios now demand exposure to SoftBank simply to maintain parity, with the stock's 15.9 trillion yen ($110 billion) value accretion dwarfing contributions from runners-up Advantest and Mitsubishi Heavy Industries combined.

Masayoshi Son's relentless AI investments have transformed SoftBank from market pariah to mandatory holding. Active managers face a brutal choice: participate in the rally or watch relative performance erode. "When a heavyweight stock like this runs, underweight positions become untenable," Nagata observed, highlighting the existential dilemma for stock-pickers in benchmark-constrained environments.