Capital World Investors holds 10.9M Alnylam shares (NASDAQ: ALNY)

Rhea-AI Filing Summary

Capital World Investors reports beneficial ownership of 10,916,799 shares (8.2%) of Alnylam Pharmaceuticals. The filing states CWI has sole voting power over 10,871,837 shares and sole dispositive power over 10,916,799 shares of the 132,623,144 shares believed outstanding as of the filing. The amendment is signed by a CRMC officer.

Insights

Institutional Ownership Analyst

Large passive stake disclosed; voting and dispositive powers are concentrated.

Capital World Investors, through its investment management entities, is reported as beneficial owner of 10,916,799 shares, representing 8.2% of the 132,623,144 shares the filing cites as outstanding. The filing lists specific voting and dispositive counts.

Concentration of sole voting and dispositive power at the reported levels is factual; any governance implications depend on future filings or public statements. Subsequent filings would show changes in position or intent.

Compliance & Disclosure Specialist

Amendment clarifies beneficial owner identity and precise holdings.

The Schedule 13G/A amendment attributes ownership to Capital World Investors and details the allocation among related investment management entities. It explicitly cites the divisional structure and the roles of affiliated entities in providing investment management services.

Filing mechanics: the document updates beneficial ownership disclosure; it does not indicate an offer, transaction, or change in control intent.

Key Figures

Beneficially owned shares: 10,916,799 shares Percent of class: 8.2% Shares outstanding (cited): 132,623,144 shares +2 more

5 metrics

Beneficially owned shares 10,916,799 shares reported in Schedule 13G/A amendment

Percent of class 8.2% of 132,623,144 shares believed outstanding

Shares outstanding (cited) 132,623,144 shares shares believed to be outstanding as cited in filing

Sole voting power 10,871,837 shares sole power to vote or to direct the vote

Sole dispositive power 10,916,799 shares sole power to dispose or to direct the disposition

Key Terms

Schedule 13G/A, beneficial owner, sole dispositive power, sole voting power

4 terms

Schedule 13G/A regulatory

"Amendment No. 3 and Schedule 13G/A heading"

A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.

beneficial owner financial

"CWI is deemed to be the beneficial owner of 10,916,799 shares"

A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.

sole dispositive power regulatory

"Sole power to dispose or to direct the disposition of: 10,916,799"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

sole voting power regulatory

"Sole power to vote or to direct the vote: 10,871,837"

Sole voting power is the exclusive right to cast votes attached to a shareholder’s stock without needing approval from anyone else. Like holding the only remote control for a TV, it lets that holder decide corporate matters such as board members, mergers, and policy changes, making it important to investors because it concentrates control and can strongly influence a company’s strategy and the value of its shares.

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

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Accepted by SEC EDGAR 05/14/2026 - 01:55 PM Learn about SEC filing dates

FAQ

What stake does Capital World Investors report in ALNY?

Capital World Investors reports beneficial ownership of 10,916,799 shares, equal to 8.2% of the 132,623,144 shares the filing cites as outstanding. The filing attributes the holdings to CWI and its affiliated investment management entities.

How many votes does Capital World Investors control in Alnylam?

The filing states CWI has sole voting power over 10,871,837 shares. It separately reports sole dispositive power over 10,916,799 shares, reflecting control and disposition authority as disclosed in the amendment.

Is this a Form 13G or 13D disclosure for ALNY?

This filing is an amended Schedule 13G/A, indicating a passive investor disclosure under Section 13(g). The amendment updates beneficial ownership details and affiliate structure rather than asserting activist intent or a control purpose.

Does the filing show when these ownership figures apply?

The amendment lists the beneficial ownership counts and states the total outstanding as 132,623,144 shares. The filing itself does not attach an explicit separate date to every count beyond the document context and signature date provided.

Who signed the Schedule 13G/A amendment for Capital World Investors?

The amendment is signed by Jae Won Chung, identified as Senior Vice President and Associate General Counsel of Capital Research and Management Company, as shown on the filing signature block.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 3)

Alnylam Pharmaceuticals, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

02043Q107

(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): 02043Q107

1

Names of Reporting Persons

Capital World Investors

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 10,871,837.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 10,916,799.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

10,916,799.00

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)

8.2 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Alnylam Pharmaceuticals, Inc.
(b)	Address of issuer's principal executive offices: 675 West Kendall Street, Henri A. Termeer Square, Cambridge, MA 02142
Item 2.
(a)	Name of person filing: Capital World Investors
(b)	Address or principal business office or, if none, residence: 333 SOUTH HOPE STREET, 55TH FLOOR, LOS ANGELES, CALIFORNIA 90071
(c)	Citizenship: N/A
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 02043Q107
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: 10,916,799 ** **Capital World Investors ("CWI") is a division of Capital Research and Management Company ("CRMC"), as well as its investment management subsidiaries and affiliates Capital Bank and Trust Company, Capital International, Inc., Capital International Limited, Capital International Sarl, Capital International K.K., Capital Group Private Client Services, Inc., and Capital Group Investment Management Private Limited (together with CRMC, the "investment management entities"). CWI's divisions of each of the investment management entities collectively provide investment management services under the name "Capital World Investors." CWI is deemed to be the beneficial owner of 10,916,799 shares or 8.2% of the 132,623,144 shares believed to be outstanding.
(b)	Percent of class: 8.2 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 10,871,837
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 10,916,799
	(iv) Shared power to dispose or to direct the disposition of: 0
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.
	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.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	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.

Capital World Investors

Signature:	Jae Won Chung
Name/Title:	Senior Vice President and Associate General Counsel, Capital Research and Management Company
Date:	05/13/2026