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Archimedes Tech SPAC Partners III Co.

ARCIU
Exchange
Nasdaq
Industry
Blank Checks
SEC CIK
0002083910

No open-market purchases or sales by Archimedes Tech SPAC Partners III Co. insiders were filed in the last 90 days; 15 institutions reported holding it in 13F filings for Q2 2026, worth $47.3M in total; no superinvestor holds it.

Other share classesARCIARCIW

13F holders, Q2 2026

Institutional positions in Archimedes Tech SPAC Partners III Co. as of Jun 30, 2026. Investment managers with $100 million or more in US stocks report their long positions on Form 13F within 45 days after each quarter ends. How 13F works

Institutional holders
15
−14 vs. Q1 2026
Shares held
4.63M
−4.47M (−49.2%) vs. Q1 2026
Total value
$47.3M
−$43.8M (−48.1%) vs. Q1 2026
New holders
1
6 more added
Sold out
15
1 more reduced

Compare with Q1 2026: new holders, sold out and not filed yet

Holders and value by quarter

Institutions reporting ARCIU on Form 13F each quarter since Q1 2021, and the total value they reported. Values are as of each quarter end, so they also move with the share price.

Institutional holdersQ2 2026: 15 institutions
Q1 2021: 0 institutionsQ2 2021: 0 institutionsQ3 2021: 0 institutionsQ4 2021: 0 institutionsQ1 2022: 0 institutionsQ2 2022: 0 institutionsQ3 2022: 0 institutionsQ4 2022: 0 institutionsQ1 2023: 0 institutionsQ2 2023: 0 institutionsQ3 2023: 0 institutionsQ4 2023: 0 institutionsQ1 2024: 0 institutionsQ2 2024: 0 institutionsQ3 2024: 0 institutionsQ4 2024: 0 institutionsQ1 2025: 0 institutionsQ2 2025: 0 institutionsQ3 2025: 0 institutionsQ4 2025: 0 institutionsQ1 2026: 29 institutionsQ2 2026: 15 institutions
Value heldQ2 2026: $47.3M
Q1 2021: $0Q2 2021: $0Q3 2021: $0Q4 2021: $0Q1 2022: $0Q2 2022: $0Q3 2022: $0Q4 2022: $0Q1 2023: $0Q2 2023: $0Q3 2023: $0Q4 2023: $0Q1 2024: $0Q2 2024: $0Q3 2024: $0Q4 2024: $0Q1 2025: $0Q2 2025: $0Q3 2025: $0Q4 2025: $0Q1 2026: $91.0MQ2 2026: $47.3M
Institutions holding ARCIU and their total value by quarter
QuarterHoldersValue
Q2 202615$47.3M
Q1 202629$91.0M
Q4 20250$0
Q3 20250$0
Q2 20250$0
Q1 20250$0
Q4 20240$0
Q3 20240$0
Q2 20240$0
Q1 20240$0
Q4 20230$0
Q3 20230$0
Q2 20230$0
Q1 20230$0
Q4 20220$0
Q3 20220$0
Q2 20220$0
Q1 20220$0
Q4 20210$0
Q3 20210$0
Q2 20210$0
Q1 20210$0

Institutions, Q2 2026

Shares, value and share of portfolio for each institution holding Archimedes Tech SPAC Partners III Co.; share changes are against Q1 2026.

Institutions holding ARCIU in Q2 2026
InstitutionSharesValue% of portfolioChange in sharesAction
LMR Partners LLP1,250,000$12.7M0.09%00.0%Unchanged
Tudor Investment Corp Et Al650,000$6.62M0.03%00.0%Unchanged
Toronto Dominion Bank646,217$6.59M0.01%+396,217+158.5%Added
Omers Administration Corp480,000$4.89M0.03%00.0%Unchanged
Aristeia Capital LLC400,779$4.08M0.06%+989+0.2%Added
Lineage Point Capital LP288,776$3.01M0.62%+13,776+5.0%Added
BlueCrest Capital Management Ltd275,000$2.82M0.12%00.0%Unchanged
Millennium Management LLC179,743$1.83M0.00%−170,257−48.6%Reduced
Qube Research & Technologies Ltd150,000$1.54M0.00%00.0%Unchanged
Calamos Advisors LLC124,000$1.29M0.00%00.0%Unchanged
Westchester Capital Management, LLC100,000$1.02M0.05%00.0%Unchanged
Clear Street Group Inc.34,256$349.1K0.00%+24,194+240.4%Added
HRT Financial LP25,000$256.0K0.00%+40.0%Added
Glazer Capital, LLC10,523$110.0K0.00%+10,523New
Tuttle Tactical Management10,769$109.4K0.07%+769+7.7%Added
Alberta Investment Management Corp0$00.00%−1,000,000−100.0%Sold out
CNH Partners LLC0$00.00%−757,625−100.0%Sold out
Rivernorth Capital Management, LLC0$00.00%−500,000−100.0%Sold out
Lighthouse Investment Partners, LLC0$00.00%−500,000−100.0%Sold out
BNP Paribas Arbitrage, SA0$00.00%−492,375−100.0%Sold out
Commonwealth of Pennsylvania Public School Empls Retrmt Sys0$00.00%−400,000−100.0%Sold out
MMCAP International Inc. SPC0$00.00%−300,000−100.0%Sold out
Schonfeld Strategic Advisors LLC0$00.00%−236,368−100.0%Sold out
Wealthspring Capital LLC0$00.00%−166,480−100.0%Sold out
Picton Mahoney Asset Management0$00.00%−150,000−100.0%Sold out
Boothbay Fund Management, LLC0$00.00%−100,000−100.0%Sold out
Bulldog Investors, LLP0$00.00%−67,500−100.0%Sold out
Abc Arbitrage SA0$00.00%−40,000−100.0%Sold out
Prelude Capital Management, LLC0$00.00%−20,000−100.0%Sold out
Stoic Point Capital Management LLC0$00.00%−20,000−100.0%Sold out