SoftBank surges to record high on anticipated OpenAI IPO

The Nikkei 225 breached the 65,000 mark for the first time on Monday, propelled almost single-handedly by a record-breaking surge in SoftBank Group shares. The Japanese investment giant has added over $60 billion to its market capitalization in just two weeks, fueled by mounting speculation that OpenAI is on the verge of filing for an initial public offering. This IPO would crystallize what is arguably the largest single bet ever placed by SoftBank’s founder, Masayoshi Son.

By midday, the Nikkei settled at 65,254, a gain of 3.02% on the session, according to The Japan Times. While easing geopolitical tensions between the United States and Iran, along with the potential resumption of shipping through the Strait of Hormuz, provided a tailwind for the broader market, the rally in SoftBank has been its own engine. That momentum began late last week, when reports surfaced that OpenAI was preparing to file confidentially for an IPO, possibly as soon as the end of last week, targeting a market debut this autumn at a valuation that could surpass $1 trillion.

SoftBank effectively trades as the only publicly listed proxy for two of the most consequential private stakes in the artificial intelligence infrastructure build-out: a roughly 13% stake in OpenAI and a controlling interest in Arm, the British chip designer. Both positions have moved dramatically in recent days. Arm surged more than 16% on Thursday, following a 15% gain the day before, after Nvidia’s earnings beat reinforced the message that hyperscaler spending on AI hardware is not slowing. SoftBank itself jumped nearly 20% on Thursday and another 12% on Friday, marking the largest two-day move by a major global company in recent memory.

The sheer scale of SoftBank’s OpenAI investment is difficult to contextualize. CFO Yoshimitsu Goto disclosed on the company’s earnings call this month that SoftBank invested $32.4 billion in OpenAI during the fiscal year ending in March. An additional $30 billion in follow-on funding has been committed, with $10 billion already disbursed in April. By October, the cumulative figure is expected to reach $64.6 billion. The structure is backed by a $40 billion bridge loan from a syndicate that has now grown to eight banks.

In fiscal 2025, SoftBank booked roughly $45.7 billion in cumulative investment gains, helping it post net income of $31.4 billion. Goto called that the highest profit ever recorded by a Japanese corporation. However, most of that value is captured in marks rather than cash. The IPO, if it materializes as anticipated, is the event that will convert that paper valuation into something closer to a real price.

There are reasons for caution, and the market is largely aware of them. Holding companies typically trade at a discount to the underlying value of their assets, and SoftBank has historically sported one of the wider discounts. The company’s net asset value, around $300 billion in mid-May, swings significantly with weekly movements in Arm and OpenAI. OpenAI’s most recent private funding round, valued at $852 billion, has also drawn scrutiny from some of the firm’s own investors, who have highlighted the gap between revenue and valuation. Reports that OpenAI missed internal revenue and user-growth targets have not derailed the rally, but they have not disappeared either.

Of the 12 analysts covering SoftBank, eight rate it a strong buy, three a hold, and one a strong sell. The average price target sits slightly below where the shares are currently trading. For the next six months, the asymmetry is procedural: the date of the IPO filing, the price range, and the eventual first-day trading mark are the key unknowns.

Son has spent much of the past year arguing, in his characteristic style, that OpenAI represents the most important technology shift of the century. Monday’s record high marks the first time the public market has agreed with him at this scale.