Company · Ownership research

Altimmune, Inc. ALT

CIK 0001326190 · CUSIP 02155H200

Insider trading Initial holdings Institutional holders

Quarter-end disclosures, not live holdings.

Several CUSIPs are reported for this company; this page shows CUSIP 02155H200 (ALT), not CUSIP 02155H900 (ALT), CUSIP 02155H950 (ALT), and does not merge CUSIPs.

This page lists the top 20 of 173 rows by value; the complete set is available through the API.

Top 20 institutions

Weight means this stock's share of the manager's own portfolio.

By reported value

#	Manager	Value	Manager weight	Change vs prior	Source
01	BlackRock, Inc. CIK 2012383 · View history	$39.41M 12,795,277 shares	0.00%	+3.09M(+31.90%)Added	SEC filing ↗ May 13, 2026	▾
02	STATE STREET CORP CIK 93751 · View history	$22.01M 7,145,550 shares	0.00%	+2.03M(+39.60%)Added	SEC filing ↗ May 15, 2026	▾
03	VANGUARD CAPITAL MANAGEMENT LLC CIK 2100119 · Amended · View history	$17.43M 5,658,049 shares	0.00%	—	SEC filing ↗ May 15, 2026	▾
04	VANGUARD PORTFOLIO MANAGEMENT LLC CIK 2100121 · Amended · View history	$16.58M 5,382,002 shares	0.00%	—	SEC filing ↗ May 8, 2026	▾
05	MARSHALL WACE, LLP CIK 1318757 · View history	$12.38M 4,017,901 shares	0.01%	+3.10M(+335.40%)Added	SEC filing ↗ May 15, 2026	▾
06	MILLENNIUM MANAGEMENT LLC CIK 1273087 · View history	$10.04M 3,258,191 shares	0.01%	+3.05M(+1,471.10%)Added	SEC filing ↗ May 15, 2026	▾
07	GEODE CAPITAL MANAGEMENT, LLC CIK 1214717 · View history	$9.57M 3,107,096 shares	0.00%	+814.69K(+35.50%)Added	SEC filing ↗ May 15, 2026	▾
08	Alyeska Investment Group, L.P. CIK 1453072 · View history	$8.15M 2,644,600 shares	0.02%	+2.64MNew	SEC filing ↗ May 15, 2026	▾
09	TWO SIGMA INVESTMENTS, LP CIK 1179392 · View history	$7.64M 2,478,900 shares	0.01%	+1.21M(+95.90%)Added	SEC filing ↗ May 15, 2026	▾
10	Nuveen, LLC CIK 1871926 · View history	$7.19M 2,334,601 shares	0.00%	+1.09M(+87.60%)Added	SEC filing ↗ Apr 30, 2026	▾
11	GOLDMAN SACHS GROUP INC CIK 886982 · View history	$4.16M 1,350,649 shares	0.00%	+1.36K(+0.10%)Added	SEC filing ↗ May 15, 2026	▾
12	SUSQUEHANNA INTERNATIONAL GROUP, LLP CIK 1446194 · View history	$4.08M 1,325,956 shares	0.01%	-43.06K(-3.10%)Reduced	SEC filing ↗ May 15, 2026	▾
13	DIMENSIONAL FUND ADVISORS LP CIK 354204 · View history	$3.22M 1,045,926 shares	0.00%	+762.22K(+268.70%)Added	SEC filing ↗ May 7, 2026	▾
14	NORTHERN TRUST CORP CIK 73124 · View history	$3.07M 996,721 shares	0.00%	+280.73K(+39.20%)Added	SEC filing ↗ May 14, 2026	▾
15	UBS Group AG CIK 1610520 · View history	$2.79M 904,768 shares	0.00%	+262.72K(+40.90%)Added	SEC filing ↗ May 5, 2026	▾
16	VANGUARD FIDUCIARY TRUST CO CIK 933478 · Amended · View history	$2.68M 869,318 shares	0.00%	—	SEC filing ↗ May 8, 2026	▾
17	MORGAN STANLEY CIK 895421 · View history	$2.39M 775,258 shares	0.00%	-584.63K(-43.00%)Reduced	SEC filing ↗ May 15, 2026	▾
18	D. E. Shaw & Co., Inc. CIK 1009207 · View history	$2.24M 727,001 shares	0.00%	-616.58K(-45.90%)Reduced	SEC filing ↗ May 15, 2026	▾
19	FMR LLC CIK 315066 · View history	$2.08M 673,964 shares	0.00%	+109.87K(+19.50%)Added	SEC filing ↗ May 15, 2026	▾
20	TANG CAPITAL MANAGEMENT LLC CIK 1232621 · View history	$2.05M 666,022 shares	0.10%	-1.47M(-68.80%)Reduced	SEC filing ↗ May 15, 2026	▾

Showing 20 / 173 institutions. The complete set is available through the API.

Coverage & totals by quarter

Reporting institutions

173

Cancelled or null records excluded

Disclosed shares

69,370,859

Not deduplicated across managers

Disclosed value

$213.51M

Not market cap or free float

Reporting institutions by quarter

Counts also change with data coverage and reporting entities; they do not measure net buying. Distinct managers with a live stock row in this CUSIP; totals may include overlapping filings and are not a share of the company.

Altimmune, Inc. · Q1 2026

Explore all 173 reporting institutions.

This page includes 20 of 173 reporting institutions. Log in to look up the full history beyond 3 years, use advanced screening & filtering, download CSV, and get the complete set through the Akkru API.

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Sources, coverage & how to read this data

Figures are as reported to the SEC and merged with later amendments where Akkru could match them. Preview limits apply to what is listed, not to the totals, which come from the complete reported data. Nothing is zero-filled: a missing quarter or month is shown as missing.