Who owns Archimedes Tech SPAC Partners II Co. Ordinary Shares (ATII)
Which tracked institutional funds hold ATII, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See ATII company fundamentals →
Ownership as of the 2026-Q2 13F filings (latest filed 2026-08-14). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
How the tape is positioned
The tracked-fund tape on ATII is one-sided between 2026-Q1 and 2026-Q2: 11 added or opened and 37 trimmed or exited — on balance reducing.
A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.
Conviction spread
ATII’s largest tracked holder by dollar value, TENOR CAPITAL MANAGEMENT Co., L.P., sizes it at 0.2% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 0.2pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in ATII divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.
Institutional & insider positioning
Between 2026-Q1 and 2026-Q2, across 43 tracked filers holding ATII, 11 increased or opened the position and 40 reduced or closed it; over the same quarter, there were no open-market insider Form 4s.
This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.
New buyers & exits
Funds opening or closing a position in ATII between the 2026-Q1 and 2026-Q2 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.
New buyers 4
- Fort Baker Capital Management LP$14M
- Shay Capital LLC$7M
- TUDOR INVESTMENT CORP ET AL$1M
- CANTOR FITZGERALD, L. P.$952K
Full exits 19
- TENOR CAPITAL MANAGEMENT Co., L.P.$16M
- Westchester Capital Management, LLC$9M
- GLAZER CAPITAL, LLC$8M
- PICTON MAHONEY ASSET MANAGEMENT$5M
- RIVERNORTH CAPITAL MANAGEMENT, LLC$4M
- RLH Capital LLC$4M
Largest adds
- K2 PRINCIPAL FUND, L.P.$5M
- CITADEL ADVISORS LLC$3M
- DLD Asset Management, LP$545K
- Magnetar Financial LLC$419K
- D. E. Shaw & Co., Inc.$376K
- Ghisallo Capital Management LLC$276K
Largest trims
- TORONTO DOMINION BANK$6M
- LMR Partners LLP$4M
- Alberta Investment Management Corp$4M
- Jain Global LLC$3M
- AQR Arbitrage LLC$3M
- MILLENNIUM MANAGEMENT LLC$2M
Institutional holders
One row per tracked fund, largest reported value first. “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding. Rows marked stale are from an earlier filing than the security’s latest quarter — that fund is absent from the newest snapshot (position exited, or reported under a different name).
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| Fort Baker Capital Management LP new | 1,330,746 | $14M | 6.0% | 2026-Q2 |
| Magnetar Financial LLC trimmed | 1,297,302 | $14M | 5.9% | 2026-Q2 |
| D. E. Shaw & Co., Inc. | 1,138,500 | $12M | 5.2% | 2026-Q2 |
| Linden Advisors LP trimmed | 848,273 | $9M | 3.9% | 2026-Q2 |
| Ghisallo Capital Management LLC | 800,000 | $9M | 3.6% | 2026-Q2 |
| TWO SIGMA INVESTMENTS, LP | 725,000 | $8M | 3.3% | 2026-Q2 |
| Hudson Bay Capital Management LP | 700,000 | $8M | 3.2% | 2026-Q2 |
| Shay Capital LLC new | 623,687 | $7M | 2.8% | 2026-Q2 |
| Governors Lane LP trimmed | 604,857 | $7M | 2.7% | 2026-Q2 |
| AQR Arbitrage LLC trimmed | 590,262 | $6M | 2.7% | 2026-Q2 |
| Sculptor Capital LP trimmed | 552,619 | $6M | 2.5% | 2026-Q2 |
| K2 PRINCIPAL FUND, L.P. added | 526,227 | $6M | 2.4% | 2026-Q2 |
| LMR Partners LLP trimmed | 478,978 | $5M | 2.2% | 2026-Q2 |
| Radcliffe Capital Management, L.P. trimmed | 478,061 | $5M | 2.2% | 2026-Q2 |
| MOORE CAPITAL MANAGEMENT, LP | 450,000 | $5M | 2.0% | 2026-Q2 |
| Alberta Investment Management Corp trimmed | 400,000 | $4M | 1.8% | 2026-Q2 |
| CITADEL ADVISORS LLC added | 250,266 | $3M | 1.1% | 2026-Q2 |
| WHITEBOX ADVISORS LLC | 250,000 | $3M | 1.1% | 2026-Q2 |
| GOLDMAN SACHS GROUP INC trimmed | 205,090 | $2M | 0.9% | 2026-Q2 |
| ARISTEIA CAPITAL, L.L.C. trimmed | 200,000 | $2M | 0.9% | 2026-Q2 |
| L1 Global Manager Pty Ltd | 200,000 | $2M | 0.9% | 2026-Q2 |
| DLD Asset Management, LP added | 195,453 | $2M | 0.9% | 2026-Q2 |
| Jain Global LLC trimmed | 185,108 | $2M | 0.8% | 2026-Q2 |
| Periscope Capital Inc. trimmed | 175,000 | $2M | 0.8% | 2026-Q2 |
| Verition Fund Management LLC trimmed | 140,797 | $2M | 0.6% | 2026-Q2 |
| MMCAP International Inc. SPC | 125,000 | $1M | 0.6% | 2026-Q2 |
| TUDOR INVESTMENT CORP ET AL new | 123,842 | $1M | 0.6% | 2026-Q2 |
| CANTOR FITZGERALD, L. P. new | 88,283 | $952K | 0.4% | 2026-Q2 |
| TORONTO DOMINION BANK trimmed | 82,550 | $890K | 0.4% | 2026-Q2 |
| Baird Financial Group, Inc. | 78,500 | $846K | 0.4% | 2026-Q2 |
| Shaolin Capital Management LLC trimmed | 76,171 | $821K | 0.3% | 2026-Q2 |
| MILLENNIUM MANAGEMENT LLC trimmed | 69,384 | $748K | 0.3% | 2026-Q2 |
| Schonfeld Strategic Advisors LLC trimmed | 50,000 | $539K | 0.2% | 2026-Q2 |
| Clear Street Group Inc. trimmed | 25,000 | $270K | 0.1% | 2026-Q2 |
| BNP PARIBAS FINANCIAL MARKETS trimmed | 23,790 | $256K | 0.1% | 2026-Q2 |
| MIZUHO SECURITIES USA LLC | 19,469 | $202K | 0.1% | 2026-Q2 |
| HIGHBRIDGE CAPITAL MANAGEMENT LLC new | 17,497 | $189K | 0.1% | 2026-Q2 |
| READYSTATE ASSET MANAGEMENT LP trimmed | 12,528 | $135K | 0.1% | 2026-Q2 |
| GEODE CAPITAL MANAGEMENT, LLC | 11,102 | $120K | 0.1% | 2026-Q2 |
| EverSource Wealth Advisors, LLC new | 8,500 | $92K | 0.0% | 2026-Q2 |
| UBS Group AG new | 1,658 | $18K | 0.0% | 2026-Q2 |
| MORGAN STANLEY trimmed | 35 | $377 | 0.0% | 2026-Q2 |
| Caitong International Asset Management Co., Ltd new | 4 | $43 | 0.0% | 2026-Q2 |
| TENOR CAPITAL MANAGEMENT Co., L.P. | 1,500,000 | $16M | 6.6% | 2026-Q1 stale (1 quarter behind) |
| Westchester Capital Management, LLC | 907,144 | $9M | 4.0% | 2026-Q1 stale (1 quarter behind) |
| GLAZER CAPITAL, LLC trimmed | 750,000 | $8M | 3.3% | 2026-Q1 stale (1 quarter behind) |
| PICTON MAHONEY ASSET MANAGEMENT | 500,000 | $5M | 2.2% | 2026-Q1 stale (1 quarter behind) |
| RIVERNORTH CAPITAL MANAGEMENT, LLC trimmed | 427,500 | $4M | 1.9% | 2026-Q1 stale (1 quarter behind) |
| RLH Capital LLC new | 400,907 | $4M | 1.8% | 2026-Q1 stale (1 quarter behind) |
| COMMONWEALTH OF PENNSYLVANIA PUBLIC SCHOOL EMPLS RETRMT SYS | 400,000 | $4M | 1.8% | 2026-Q1 stale (1 quarter behind) |
| J. Goldman & Co LP new | 369,778 | $4M | 1.6% | 2026-Q1 stale (1 quarter behind) |
| Mint Tower Capital Management B.V. | 300,000 | $3M | 1.3% | 2026-Q1 stale (1 quarter behind) |
| METEORA CAPITAL, LLC trimmed | 295,612 | $3M | 1.3% | 2026-Q1 stale (1 quarter behind) |
| Centiva Capital, LP | 285,515 | $3M | 1.3% | 2026-Q1 stale (1 quarter behind) |
| Quarry LP new | 285,000 | $3M | 1.3% | 2026-Q1 stale (1 quarter behind) |
| BERKLEY W R CORP trimmed | 208,065 | $2M | 0.9% | 2026-Q1 stale (1 quarter behind) |
| O'Connor Alternative Investments LLC new | 200,000 | $2M | 0.9% | 2026-Q1 stale (1 quarter behind) |
| WOLVERINE ASSET MANAGEMENT LLC trimmed | 134,280 | $1M | 0.6% | 2026-Q1 stale (1 quarter behind) |
| GRITSTONE ASSET MANAGEMENT LLC | 99,081 | $1M | 0.4% | 2026-Q1 stale (1 quarter behind) |
| Lineage Point Capital LP new | 95,895 | $1M | 0.4% | 2026-Q1 stale (1 quarter behind) |
| CSS LLC/IL | 57,143 | $595K | 0.3% | 2026-Q1 stale (1 quarter behind) |
| Virtu Financial LLC new | 53,686 | $561K | 0.2% | 2026-Q1 stale (1 quarter behind) |
| Driehaus Capital Management LLC | 573,083 | $6M | 2.5% | 2025-Q4 stale (2 quarters behind) |
| OCONNOR, A Distinct Business Unit of UBS ASSET MANAGEMENT AMERICAS (LLC) new | 200,000 | $2M | 0.9% | 2025-Q4 stale (2 quarters behind) |
| StoneX Group Inc. new | 50,613 | $524K | 0.2% | 2025-Q4 stale (2 quarters behind) |
| Warberg Asset Management LLC | 10,000 | $104K | 0.0% | 2025-Q4 stale (2 quarters behind) |
| CLEAR STREET LLC new | 37,534 | $384K | 0.2% | 2025-Q2 stale (4 quarters behind) |
| CONCOURSE FINANCIAL GROUP SECURITIES, INC. new | 0 | — | 0.0% | 2025-Q2 stale (4 quarters behind) |
Ownership over time
Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.
Reading this table
Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.
About 13F filings
A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.