Janus Henderson Group (JATT) discloses 6.2% beneficial stake in JATT II

Rhea-AI Filing Summary

Janus Henderson Group Ltd. reports beneficial ownership of 500,000 ordinary shares of JATT II Acquisition Corp., representing 6.2% of the class. The position is held through various affiliated asset managers that exercise investment and/or voting discretion for client accounts referred to as Managed Portfolios.

Janus Henderson has no sole voting or dispositive power over these shares, but shared voting and dispositive power over 500,000 shares. The asset managers disclaim rights to receive dividends or sale proceeds, which belong to the Managed Portfolios. Among these, Janus Henderson Biotech Innovation Master Fund Ltd. alone has the right to receive dividends or proceeds relating to more than five percent of JATT II’s ordinary shares.

Key Figures

Shares beneficially owned: 500,000 ordinary shares Percent of class: 6.2% Shared voting power: 500,000 shares +3 more

6 metrics

Shares beneficially owned 500,000 ordinary shares Beneficial ownership of JATT II Acquisition Corp. ordinary shares by Janus Henderson Group Ltd.

Percent of class 6.2% Percentage of JATT II Acquisition Corp. ordinary shares beneficially owned

Shared voting power 500,000 shares Shares over which Janus Henderson has shared power to vote or direct the vote

Shared dispositive power 500,000 shares Shares over which Janus Henderson has shared power to dispose or direct disposition

Sole voting power 0 shares Shares over which Janus Henderson has sole voting power

Sole dispositive power 0 shares Shares over which Janus Henderson has sole dispositive power

Key Terms

beneficial owner, Managed Portfolios, dispositive power, Power of Attorney, +1 more

5 terms

beneficial owner financial

"the Asset Managers may be deemed to be the beneficial owner of 500,000 ordinary 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.

Managed Portfolios financial

"clients which include investment companies... collectively referred to herein as Managed Portfolios"

dispositive power financial

"Sole Dispositive Power 0.00 8 | Shared Dispositive Power 500,000.00"

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.

Power of Attorney regulatory

"Exhibit 24: Power of Attorney"

A power of attorney is a legal document that allows one person to make decisions and act on behalf of another person, often in financial or legal matters. It’s like giving someone a trusted helper or agent the authority to handle important tasks if you are unable to do so yourself. This matters to investors because it can impact how their assets are managed or transferred if they become unable to oversee their affairs.

irrevocable delegation financial

"Due to an irrevocable delegation of investment and voting discretion"

FAQ

What stake does Janus Henderson hold in JATT (JATT II Acquisition Corp.)?

Janus Henderson Group Ltd. is deemed the beneficial owner of 500,000 ordinary shares of JATT II Acquisition Corp., representing 6.2% of the outstanding class, through investment discretion exercised by its affiliated asset managers over client accounts.

How much voting power does Janus Henderson report in JATT (JATT II Acquisition Corp.)?

Janus Henderson reports 0 shares with sole voting power and 500,000 shares with shared voting power in JATT II Acquisition Corp., reflecting its role through affiliated asset managers acting for Managed Portfolios rather than for its own account.

Who receives dividends and sale proceeds from the JATT shares managed by Janus Henderson?

All dividends and sale proceeds from the 500,000 JATT II shares are payable to the Managed Portfolios. Janus Henderson’s asset managers exercise discretion but disclaim economic ownership of these securities held for their clients.

Which Janus Henderson fund holds more than 5% of JATT’s ordinary shares?

Among the Managed Portfolios, only Janus Henderson Biotech Innovation Master Fund Ltd. has the right to receive dividends or sale proceeds from more than five percent of JATT II Acquisition Corp.’s ordinary shares, due to its holdings.

Where is Janus Henderson Group Ltd. organized and where is its principal office for this JATT holding?

Janus Henderson Group Ltd. is organized in Jersey, with a principal business office at 201 Bishopsgate, EC2M 3AE, United Kingdom, from which it oversees affiliated asset managers responsible for the JATT II share holdings.

What dispositive power does Janus Henderson report over its JATT (JATT II) shares?

Janus Henderson reports 0 shares with sole dispositive power and 500,000 shares with shared dispositive power. This reflects authority exercised by its affiliated asset managers over client accounts rather than direct proprietary ownership.

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

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Available on EDGAR 08/13/2026 - 12:30 PM Accepted by SEC EDGAR 08/13/2026 - 12:30 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

JATT II ACQUISITION CORP.

(Name of Issuer)

Ordinary Shares

(Title of Class of Securities)

G50765109

(CUSIP Number)

06/30/2026

(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): G50765109

1

Names of Reporting Persons

JANUS HENDERSON GROUP Ltd.

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 500,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 500,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

500,000.00

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)

6.2 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

Item 1.
(a)	Name of issuer: JATT II ACQUISITION CORP.
(b)	Address of issuer's principal executive offices: 153 CENTRAL AVENUE, C/O 56 WESTFIELD, NJ 07091
Item 2.
(a)	Name of person filing: Janus Henderson Group Ltd. In accordance with SEC Release No. 34-39538 (January 12, 1998), this Schedule 13G reflects the securities beneficially owned, or deemed to be beneficially owned, by Janus Henderson Group Ltd. It does not include securities, if any, beneficially owned by Janus Henderson Group Ltd.s ultimate parent Jupiter Topco LLC, the direct or indirect owners of Jupiter Topco LLC, or other persons that may be deemed under control of such owners. Any beneficial ownership by such persons has been disaggregated from that of Janus Henderson Group Ltd. in accordance with the release.
(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: Ordinary Shares
(e)	CUSIP Number(s): G50765109
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 Ltd. (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, Victory Park Capital Advisors LLC, and Richard Berstein 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 500,000 ordinary shares of JATT II Acquisition Corp. 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: 6.2 %
(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: 500000
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 500000
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, only the Janus Henderson Biotech Innovation Master Fund Ltd. has the right to receive dividends from, or the proceeds from the sale of, more than five percent of the ordinary shares of JATT II Acquisition Corp. Due to an irrevocable delegation of investment and voting discretion to an Asset Manager on less than 60 days notice, the Fund is not considered a Reporting Person under Section 13(d) and (g).
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)(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. 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.

JANUS HENDERSON GROUP Ltd.

Signature:	Kristin Mariani
Name/Title:	Head of North America Compliance
Date:	08/13/2026

Exhibit Information

Exhibit 24: Power of Attorney Exhibit 99: Item 7