NasdaqFinancialsBlank ChecksCLAYMONT, DE

Archimedes Tech SPAC Partners III Co. ARCI

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Estimated market cap $355.09M35.26M shares, shares as of Aug 12, 2026CIK 2083910

Insider trades, 12 mo

2 buys · 0 sells

$0 bought, open market

Congress trades, 24 mo

—

No disclosed trades

13F holders, Q2 2026

57.4% of shares · 9 added

13F holders

…

Lobbying, 12 mo

—

No lobbying filings

Federal contracts, 12 mo

—

None matched

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Latest 10-Q

Q2 2026

What changed in Archimedes Tech SPAC Partners III Co.'s latest quarterly report, compared with the one before.

Filed Aug 13, 2026 · Quarter ended Jun 30, 2026

Compared with the 10-Q for the quarter ended Mar 31, 2026. Sections compared: management's discussion, risk factors, legal proceedings and controls and procedures.

Read the 10-Q on sec.gov ↗Filing index ↗

Latest 10-Q

What changed in Archimedes Tech SPAC Partners III Co.'s latest quarterly report, compared with the one before.

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IPO prospectus

Priced

Archimedes Tech SPAC Partners III Co.’s initial public offering: where it stands and what the registration statement says.

Priced · Proposed ticker ARCIU, Nasdaq Global Market · First filed Dec 23, 2025 · Priced Jan 26, 2026

Raised

$240.0M

price times shares, before any over-allotment

Price per share

$10.00

on the final prospectus

Shares offered

24.00M

base offering

Read from the S-1/A filed Jan 20, 2026 · Read it on sec.gov ↗

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AI summary of the prospectus. Written by AI from the parts of the prospectus listed in the filing, and checked against its text. This is information, not investment advice.

All filings of this IPO Read the S-1/A on sec.gov ↗

IPO prospectus

Archimedes Tech SPAC Partners III Co.’s initial public offering: where it stands and what the registration statement says.

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Insider trades

2 in 12 mo

Open-market trades from Form 4. 10b5-1 marks a plan set in advance.

No open-market insider trades reported since Jan 26, 2026. Insiders have two business days to file.

Recent insider trades

Archimedes Tech SPAC Sponsors III LLC 10% owner	Jan 26 Form 4 ↗	Buy	— 390,000 sh	—
Long Long Chief Executive Officer, Director, 10% owner	Jan 26 Form 4 ↗	Buy	— 390,000 sh	—

All ARCI insider trades →Planned sales (Form 144): see notices

Insider trades

Open-market trades from Form 4. 10b5-1 marks a plan set in advance.

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13F holders

20.24M shares

52 funds report ARCI. Values checked against market prices.

Funds own 57% of shares (Q2 2026)

52 funds hold the stock.

Q3 2026: 20% · 5,560 of ~8,900 funds reported so far

Q1 202644%
Q2 202657%
Q3 2026 (so far)20%

Reports for the quarter ending Sep 30, 2026 are still coming in (21 positions so far, against 53 the quarter before), so we compare the two complete quarters before it.

Q2 2026. 16 new, 9 added to, 4 trimmed, 4 exited since Q1 2026.

Top 13F holders
#
1	Adage Capital Partners GP, LLC 13F ↗	1.80M	$18.0M	unchanged
2	Linden Advisors LP 13F ↗	1.20M	$12.0M	unchanged
3	Magnetar Financial LLC 13F ↗	1.20M	$12.0M	unchanged
4	Governors Lane LP 13F ↗	1.15M	$11.5M	+14.7%
5	Tenor Capital Management Co., L.P. 13F ↗	1.00M	$10.0M	unchanged
6	Alberta Investment Management Corp 13F ↗	1.00M	$10.0M	New
7	Verition Fund Management LLC 13F ↗	815,355	$8.2M	+8.7%
8	Sona Asset Management (us) LLC 13F ↗	800,000	$8.0M	unchanged
9	AQR Arbitrage LLC 13F ↗	757,612	$7.6M	New
10	Healthcare of Ontario Pension Plan Trust Fund 13F ↗	550,000	$5.5M	unchanged

Download CSV Every fund that holds ARCI, not only these ten. A download holds at most 10,000 rows; narrow the filters to get a smaller slice.

13F holders

Funds that report this stock, checked against market prices.

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Trades by members of Congress

Disclosed in dollar ranges, up to 45 days after the trade.

No recent congressional trades for this company.

Trades by members of Congress

Disclosed in dollar ranges, up to 45 days after the trade.

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Lobbying

What Archimedes Tech SPAC Partners III Co. and its lobbying firms report each quarter.

No recent lobbying filings for this company.

Lobbying

What Archimedes Tech SPAC Partners III Co. and its lobbying firms report each quarter.

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Institutional ownership over time

How many funds reported holding the stock at the end of each quarter, and how many shares they held between them.

Funds holding the stock

Shares they report

Funds holding the stock by quarter

Q1 2026	40	—	15.57M	$153.3M
Q2 2026	52	+12	20.24M	$202.6M
Q3 2026	21	-31	6.95M	$70.1M

Each point is a quarter-end, from Q1 2026 to Q3 2026. A fund's 13F lists its long positions in US-listed securities as of the last day of the quarter and arrives up to 45 days later, so each point shows holdings at quarter-end, not on the day they were reported.

Common shares only; options and bonds are left out. When a fund amends a report, the amended version is the one counted.

The history follows the company's current CUSIP number (G0453R105). If the company's shares were ever re-issued under a different CUSIP, the quarters before the change are not part of this series, so the first point (Q1 2026) can be later than the stock's first appearance in 13F reports.

Share counts are adjusted for stock splits; none took place between these quarters. Values are in dollars as reported at the time and are not adjusted.

A quarter appears once our daily update has built its summary. If a summary cannot be built, older reports are kept and the chart shows the quarters it has until the next update repairs it.

Institutional ownership over time

How many funds reported holding the stock at the end of each quarter, and how many shares they held between them.

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More filings and data

Each opens the table.

Ownership stakes1 in 12 mo 8-K eventsNone in 90 days PatentsNone on record Short interestFINRA · updated Oct 15 Planned insider salesNone in 12 mo Executive payNone on record Wikipedia attentionNone on record SEC enforcementNone on record IPO history2 registrations Ownership stakes…8-K events…Patents…Short interest…Planned insider sales…Executive pay…Wikipedia attention…SEC enforcement…

About the company

The basics from the company’s SEC registration.

Legal name: Archimedes Tech SPAC Partners III Co.
Address: 2093 PHILADELPHIA PIKE 1968, CLAYMONT, DE 19703
Phone: 619-719-1810
Fiscal year ends: Dec 31
Filer category: Non-accelerated filer, smaller reporting company, emerging growth company
Incorporated in: Cayman Islands
Listed as: ARCI (Nasdaq), ARCIU (Nasdaq), ARCIW (Nasdaq)
SEC filings: All filings on SEC EDGAR ↗

About the company

The basics from the company’s SEC registration.

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$10.07$0.00 (0.00%) Nov 13 close

1M3M1Y

Oct 13, 2026Low $10.03 · High $10.08Nov 13, 2026

Aug 13, 2026Low $10.03 · High $10.17Nov 13, 2026

May 28, 2026Low $9.97 · High $10.17Nov 13, 2026

Congress purchase Congress sale Insider sale over $1M

Adjusted for stock splits; not for dividends. Where prices come from.

Live chart

Intraday and historical prices from TradingView. Quotes may be delayed.

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Information, not investment advice. Company matching is automatic; check the source before relying on one row.