Key points
- Leopold Aschenbrenner's Situational Awareness built a Taiyo Yuden (TYOYY) stake that peaked at 16.61% on July 22, worth over $2 billion then.
- Taiyo Yuden makes the MLCC capacitors AI servers run on, up to 28,000 per server; its profit rose about 5.4x last year.
- As the fund hit margin calls, the stake fell to 4.41% by Aug. 3, back under Japan's 5% disclosure line.
- Nine reports filed Aug. 12 revealed the whole round trip; Tokyo shares still jumped about 7%.
Most of what we track from Leopold Aschenbrenner's fund shows up in US filings. This one landed in Japan. On Tuesday, Situational Awareness filed nine separate reports with Japan's Kanto Local Finance Bureau. It had quietly built one of its largest bets in a Japanese company few of us Americans know about.
Situational Awareness is the AI-focused fund run by Aschenbrenner, the former OpenAI researcher. We've written about him a lot lately, mostly because it nearly came apart. A sharp decline in chip stocks in late July set off margin calls; the fund's assets fell from about $45 billion to about $10 billion, and it sold its US stock book to Ken Griffin's Citadel at distressed prices. The Japanese stake is that same story.
The company is Taiyo Yuden, ticker 6976 in Tokyo and TYOYY in the over-the-counter market here. It makes multilayer ceramic capacitors, or MLCCs. These are passive parts about the size of a grain of rice, and a single high-end AI server can need as many as 28,000 of them. Taiyo Yuden and Murata supply most of the world's top-tier, which turns two Japanese parts makers into a bottleneck for the entire AI server build-out. Demand has run so hot that Taiyo Yuden's profit for the year that ended in March rose about 5.4 times, to 14.8 billion yen, or roughly $100 million. Its president, Katsuya Sase, put the order volumes plainly. "The volumes we are seeing right now are scary," he told Bloomberg in May.
Here's the part that made me want to write about it. The fund didn't ease in. It crossed Japan's 5 percent disclosure line in late June and kept buying, and by July 22 it held 16.61 percent of the company.
| Date | Situational Awareness stake in Taiyo Yuden |
|---|---|
| June 29 | 5.99% (crosses Japan's 5% line) |
| July 22 | 16.61% (peak) |
| July 30 | 15.22% (Citadel sale reported) |
| Aug. 3 | 4.41% (back below 5%) |
Then the crisis hit. Situational Awareness still owned 15.22 percent on July 30, the day its Citadel sale was reported, so the Japanese position walked into that weekend nearly whole. By August 3 it was down to 4.41 percent, below the line where Japan stops requiring disclosure. Most of the selling in Taiyo Yuden came just after the Citadel deal, on separate dates, rather than as part of it. And August 3 is the same day the fund used for its block sales of Core Scientific (CORZ) in the US. On one day, on both sides of the Pacific, Aschenbrenner was selling.
A 16.6 percent stake is a lot of one company. At Taiyo Yuden's market value today, near $8.4 billion, that slice would be worth about $1.4 billion. The shares traded roughly twice as high in late July before they lost about half their value, so at the peak the position was worth well over $2 billion. For a fund that topped out around $45 billion, that's a real concentration in a single Japanese parts maker, and it sits among the largest positions the fund has disclosed anywhere. Asia has been a theme for him this summer. His fund was also named a cornerstone investor in SK Hynix's US listing.
The timing is the strange part. All nine reports were filed on August 12, more than a month after Japan's deadline for flagging a 5 percent position. So Tokyo only learned about the 16.6 percent stake this week, after the fund had already reduced its stake to 4.41 percent. The shares jumped as much as 7 percent on the news anyway, and the US-listed shares rose even more. Investors bid up a position that, by the fund's own filings, was mostly gone.
Japan stops requiring reports if you own less than 5 percent, the same way as the US. So 4.41 percent on August 3 is the last real number we have. The fund could have kept selling, or it could have started buying again. We won't know unless it crosses back over 5 percent, or discloses the position some other way. What the filings do settle is this. The most talked-about AI investor of the year reached past the chips and the data centers, all the way down to the company that makes the capacitors those data centers can't run without.
Sources
- Situational Awareness LP large-shareholding change reports for Taiyo Yuden (6976), filed with Japan's Kanto Local Finance Bureau, Aug. 12, 2026.
- Bloomberg and Investing.com, on the disclosure and the Tokyo and US share moves, Aug. 12, 2026.
- Taiyo Yuden results for the fiscal year ended March 2026, and CEO Katsuya Sase's comments to Bloomberg, May 2026.
- Our earlier coverage of the fund's sale to Citadel and its Core Scientific block trades.
