Janus Henderson Group plc reported beneficial ownership of 4,774,841 shares of Lantheus Holdings, Inc. The filing states the Asset Managers managed by Janus Henderson may be deemed beneficial owners of 4,774,841 shares, representing 7.4% of common stock as of 03/31/2026. The Asset Managers report shared voting and dispositive power over those shares and disclaim rights to dividends or sale proceeds for the underlying Managed Portfolios. The filing is an amendment (No. 8) and attaches exhibits identifying relevant subsidiaries.
Positive
None.
Negative
None.
Insights
Large passive stake reported by Janus Henderson with shared control over 7.4% of LNTH.
Janus Henderson Group plc discloses that its Asset Managers collectively have shared voting and dispositive power for 4,774,841 shares of Lantheus Holdings, representing 7.4% of the class as of 03/31/2026. The report clarifies these holdings arise from managed client accounts rather than direct proprietary ownership.
Cash‑flow treatment and identity of specific managed accounts are not detailed in the excerpt; subsequent filings or attached exhibits may specify the subsidiaries and account types referenced in Item 7.
Amendment clarifies parent and adviser relationships and voting/dispositive allocations.
The Schedule 13G/A identifies Janus Henderson Group plc as the ultimate parent and lists multiple SEC‑registered investment advisers that exercise voting/dispositive discretion on behalf of Managed Portfolios. It reports shared voting power and shared dispositive power of 4,774,841 shares.
The filing attaches Exhibit 99 for Item 7 identification of the acquiring subsidiary; review of that exhibit will confirm which subsidiary executed the acquisition.
Key Figures
Shares beneficially owned:4,774,841 sharesPercent of class:7.4%Sole voting power:0 shares+4 more
7 metrics
Shares beneficially owned4,774,841 sharesBeneficial ownership reported as of 03/31/2026
Percent of class7.4%Percent of common stock reported in Schedule 13G/A
Sole voting power0 sharesSole power to vote reported in Item 4(c)(i)
Shared voting power4,774,841 sharesShared power to vote reported in Item 4(c)(ii)
CUSIP516544103Identifier for Lantheus common stock
"may be deemed to be the beneficial owner of 4,774,841 common stock"
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.
Managed Portfoliosfinancial
"Managed Portfolios which include investment companies, other investment advisers, institutional separate accounts"
Janus Henderson reports beneficial ownership of 4,774,841 shares, equal to 7.4% of Lantheus common stock as of 03/31/2026. The holdings are held in managed client accounts under several named Asset Managers.
Does Janus Henderson have sole voting control over LNTH shares?
No. The filing states 0 shares with sole voting power and 4,774,841 shares with shared voting power. Voting authority is exercised jointly by the Asset Managers on behalf of managed portfolios.
Will Janus Henderson receive dividends or sale proceeds from these LNTH shares?
The Asset Managers state they do not have the right to receive dividends or sale proceeds for securities held in the Managed Portfolios and disclaim ownership associated with those rights. The Managed Portfolios, not the Asset Managers, have those economic rights.
What subsidiaries or advisers are listed as exercising discretion?
The filing names multiple advisers including Janus Henderson Investors US LLC, Janus Henderson Investors (Jersey) Limited, Kapstream Capital Pty Limited, and others. Exhibit 99 is referenced for Item 7 subsidiary identification.
What does Amendment No. 8 indicate about the filing?
This is an amendment that restates or updates prior Schedule 13G information and attaches exhibits; it confirms the same beneficial ownership totals and clarifies parent/adviser classifications and related exhibits.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 8)
LANTHEUS HOLDINGS, INC.
(Name of Issuer)
Common Stock
(Title of Class of Securities)
516544103
(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):
516544103
1
Names of Reporting Persons
JANUS HENDERSON GROUP PLC
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
JERSEY
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
4,774,841.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
4,774,841.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
4,774,841.00
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)
7.4 %
12
Type of Reporting Person (See Instructions)
HC
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
LANTHEUS HOLDINGS, INC.
(b)
Address of issuer's principal executive offices:
201 BURLINGTON ROAD, SOUTH BUILDING
BEDFORD, MA 01730
Item 2.
(a)
Name of person filing:
Janus Henderson Group plc
(b)
Address or principal business office or, if none, residence:
201 Bishopsgate
EC2M 3AE, United Kingdom
(c)
Citizenship:
Y9
(d)
Title of class of securities:
Common Stock
(e)
CUSIP No.:
516544103
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:
Janus Henderson Group plc (JHG) is the ultimate parent of a number of SEC-registered investment advisers and foreign equivalents thereof, including but not limited to Janus Henderson Investors US LLC, Janus Henderson Investors UK Limited, Janus Henderson Investors Australia Institutional Funds Management Limited, Janus Henderson Investors Middle East Limited, Janus Henderson Investors (Jersey) Limited, Janus Henderson Investors (Japan) Limited, Janus Henderson Investors (Singapore) Limited, Kapstream Capital Pty Limited, Privacore Capital Advisors LLC, Tabula Investment Management Limited, and Victory Park Capital Advisors LLC (each, an Asset Manager and together, the Asset Managers). The Asset Managers generally exercise investment and/or voting discretion on behalf of their clients which include investment companies, other investment advisers, institutional separate accounts and retail separate accounts (collectively referred to herein as Managed Portfolios).
As a result of their exercise of investment and/or voting discretion on behalf of the Managed Portfolios, the Asset Managers may be deemed to be the beneficial owner of 4,774,841 common stock of Lantheus Holdings, Inc. However, the Asset Managers do not have the right to receive any dividends from, or the proceeds from the sale of, the securities held in the Managed Portfolios and disclaim any ownership associated with such rights.
(b)
Percent of class:
7.4 %
(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:
4774841
(iii) Sole power to dispose or to direct the disposition of:
0
(iv) Shared power to dispose or to direct the disposition of:
4774841
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.
The Managed Portfolios have the right to receive all dividends from, and the proceeds from the sale of, the securities held in their respective accounts.
Of the Managed Portfolios, none own more than five percent of the common stock of Lantheus Holdings, Inc.
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.
Please refer to Exhibit 99.
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)(J), so indicate under Item 3(j) 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.
N/A
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.
N/A
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.
