State Street reports 5.5% stake in Altimmune

State Street Corporation reports shared beneficial ownership of 5.5% of Altimmune Inc. common stock.

Rhea-AI Filing Summary

State Street Corporation reports shared beneficial ownership of 5.5% of Altimmune Inc. common stock. The filing states 7,145,550 shares as the number of shares for which State Street has shared dispositive power, with 7,012,433 shares of shared voting power, as of 03/31/2026. The schedule identifies affiliated investment-advisory subsidiaries and is signed by Elizabeth Schaefer, Senior Vice President and Chief Accounting Officer, on 05/12/2026.

Insights

Institutional Ownership Analyst

Large passive holder reports a 5.5% stake via shared voting and dispositive power.

State Street Corporation's Schedule 13G shows 7,145,550 shares of common stock where it holds shared dispositive power and 7,012,433 shares of shared voting power, as of 03/31/2026. The filing lists affiliated investment-advisory subsidiaries as the reporting entities.

This filing is typical for institutional asset managers and signals passive or index-related ownership rather than an active takeover intent. Subsequent filings would show changes in percentage or conversion to a Schedule 13D if strategy shifts.

Regulatory & Compliance Advisor

The Schedule 13G disclosure aligns with investment-adviser reporting obligations for >5% holdings.

The form names SSGA Funds Management, State Street Global Advisors Europe Limited, and State Street Global Advisors Trust Company as related subsidiaries. Item disclosures show 0 sole voting/dispositive power and material shared powers, consistent with pooled/managed accounts.

Filing mechanics and signature by a senior officer on 05/12/2026 complete the disclosure; any future material change in ownership or intent would require an updated filing under applicable SEC rules.

Key Figures

Beneficially owned: 7,145,550 shares Percent of class: 5.5% Shared voting power: 7,012,433 shares +4 more

7 metrics

Beneficially owned 7,145,550 shares Amount beneficially owned (Item 4)

Percent of class 5.5% Percent of class (Item 4)

Shared voting power 7,012,433 shares Shared power to vote or to direct the vote (Item 4(ii))

Shared dispositive power 7,145,550 shares Shared power to dispose or direct disposition (Item 4(iv))

Sole powers 0 shares Sole voting and sole dispositive power (Item 4(i) and 4(iii))

Reporting as of date 03/31/2026 Reporting date shown near CUSIP/header

Signature date 05/12/2026 Filing signed by Elizabeth Schaefer

Key Terms

Schedule 13G, Beneficial ownership, Dispositive power, Shared voting power

4 terms

Schedule 13G regulatory

"Item 1. (a) Name of issuer: ALTIMMUNE INC"

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

Beneficial ownership regulatory

"Item 4. (a) Amount beneficially owned: 7145550.00"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

Dispositive power regulatory

"Item 4. (iv) Shared power to dispose or to direct the disposition of: 7,145,550"

Dispositive power is the authority to decide the final outcome of an asset, legal claim, contract, or corporate action — in effect the power to dispose of or resolve something. For investors it matters because whoever holds that authority can determine who gets paid, who controls an asset or vote, and how risks and returns are allocated; think of it like holding the key that lets you lock in the winner or loser in a deal.

Shared voting power regulatory

"Item 4. (ii) Shared power to vote or to direct the vote: 7,012,433"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What stake does State Street report in Altimmune (ALT)?

State Street reports beneficial ownership of 7,145,550 shares, representing 5.5% of Altimmune common stock as of 03/31/2026. The filing lists shared voting power of 7,012,433 shares and shared dispositive power of 7,145,550 shares.

Does State Street have sole voting power over ALT shares?

No. The filing shows 0 shares with sole voting power and 0 shares with sole dispositive power. All disclosed voting and dispositive powers are reported as shared in the Schedule 13G.

Which State Street entities are named in the Schedule 13G for ALT?

The filing lists affiliated investment-adviser entities including SSGA Funds Management, Inc., State Street Global Advisors Europe Limited, and State Street Global Advisors Trust Company as the subsidiaries associated with the reported holdings.

When was the Schedule 13G for Altimmune signed?

The Schedule 13G is signed by Elizabeth Schaefer, Senior Vice President and Chief Accounting Officer, on 05/12/2026, reflecting the reporting of holdings as of 03/31/2026.

Does this Schedule 13G indicate activist intent by State Street in ALT?

No. The Schedule 13G structure and the disclosure of shared powers are consistent with passive or advisory ownership reporting; the filing does not assert activist intent or control actions.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/12/2026 - 09:46 AM EDT Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

ALTIMMUNE INC

(Name of Issuer)

COMMON STOCK

(Title of Class of Securities)

02155H200

(CUSIP Number)

03/31/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 02155H200

1

Names of Reporting Persons

STATE STREET CORPORATION

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

MASSACHUSETTS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 7,012,433.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 7,145,550.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

7,145,550.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.5 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

Item 1.
(a)	Name of issuer: ALTIMMUNE INC
(b)	Address of issuer's principal executive offices: 910 CLOPPER ROAD SUITE 201S, GAITHERSBURG, MARYLAND, 20878
Item 2.
(a)	Name of person filing: STATE STREET CORPORATION;
(b)	Address or principal business office or, if none, residence: ONE CONGRESS STREET, SUITE 1, BOSTON MA 02114, UNITED STATES
(c)	Citizenship: MA
(d)	Title of class of securities: COMMON STOCK
(e)	CUSIP Number(s): 02155H200
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 7145550.00
(b)	Percent of class: 5.5 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 7,012,433
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 7,145,550
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. NOT APPLICABLE
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary. SSGA FUNDS MANAGEMENT, INC. (IA);STATE STREET GLOBAL ADVISORS EUROPE LIMITED (IA);STATE STREET GLOBAL ADVISORS TRUST COMPANY (IA);
Item 8.	Identification and Classification of Members of the Group.
	If a group has filed this schedule pursuant to §240.13d-1(b)(1)(ii)(K), so indicate under Item 3(k) and attach an exhibit stating the identity and Item 3 classification of each member of the group. If a group has filed this schedule pursuant to §240.13d-1(c) or §240.13d-1(d), attach an exhibit stating the identity of each member of the group. NOT APPLICABLE
Item 9.	Notice of Dissolution of Group.
	Notice of dissolution of a group may be furnished as an exhibit stating the date of the dissolution and that all further filings with respect to transactions in the security reported on will be filed, if required, by members of the group, in their individual capacity. See Item 5. NOT APPLICABLE

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

STATE STREET CORPORATION

Signature:	ELIZABETH SCHAEFER
Name/Title:	SENIOR VICE PRESIDENT, CHIEF ACCOUNTING OFFICER
Date:	05/12/2026