Tokyo, 22 September 2025 — SoftBank Group Corp. has surged about 146% since the start of its fiscal year in April, driven largely by founder Masayoshi Son’s bold bets on artificial intelligence. That rally has pushed SoftBank’s weight in Japan’s Topix index to nearly 2%, up from a much smaller share just months ago — putting it in the company of blue-chip names like Toyota Motor Corp. and Sony Group Corp. This growing influence is compelling even doubters and cautious investors to buy the stock.
Investors who had long questioned SoftBank’s complex corporate structure or perceived volatility are now finding themselves almost forced to get exposure, if only to keep up with index trends. With SoftBank accounting for nearly 10% of Topix’s market-cap gains since the end of March, its rise is not just a performance story but one of structural importance to investors aiming to beat benchmark returns.
One of SoftBank’s biggest strengths this year has been its sharpened focus on AI. The markets have taken notice of its investments — including its partnership with OpenAI through the Stargate initiative and a surprise US$2 billion wager on Intel. These moves are not only boosting investor confidence but are also prompting fund managers to adjust their holdings, even if their conviction in SoftBank’s path was once tempered.
Analysts point to another interesting dynamic: SoftBank shares are trading at about a 20% discount to net asset value (NAV), a narrower gap than seen in recent years. Some believe this gap could close, particularly as Vision Fund investments begin showing stronger results and AI-driven initiatives like those with OpenAI sharpen their execution.
But all is not unqualified optimism. SoftBank’s stock tends to amplify market swings: its beta — a measure of how sensitively it moves relative to the market — is among the highest of Japan’s top 100 listed companies, meaning in downturns, weakness in SoftBank stock can hit portfolios harder. For many institutional investors, balancing the upside with material risk remains a key concern.
Despite those risks, pressure from index-linked funds and benchmark-aware managers is behaving like a magnetic pull: as long as SoftBank keeps delivering outsized performance, its large weight means under-owners are being nudged to buy just to avoid being left behind. Many analysts have raised their target prices on SoftBank in recent weeks, assuming continued stabilisation and improvement in its AI-related investments.
