American Century and Stowers Disclose 4.8% Stake in NWE

Rhea-AI Filing Summary

American Century Investment Management, Inc., American Century Companies, Inc., and the Stowers Institute for Medical Research report they beneficially own 2,952,214 shares of Northwestern Energy Group, Inc., representing 4.8% of the outstanding common stock. The filers disclose sole voting power over 2,838,388 shares and sole dispositive power over 2,952,214 shares. The filing states these securities are held in the ordinary course of business and were not acquired to change or influence control of the issuer.

The filing also clarifies that ACIM is a wholly owned subsidiary of ACC and that ACC is controlled by the Stowers Institute, explaining the relationship among the reporting entities and their shared disclosure.

Positive

• Disclosure of beneficial ownership of 2,952,214 shares (4.8%), increasing transparency for investors
• Sole voting power over 2,838,388 shares and sole dispositive power over 2,952,214 shares is clearly stated
• Filing affirms shares are held in the ordinary course and not to influence control, reducing activist concern
• Clarifies corporate relationship (ACIM is a wholly-owned subsidiary of ACC; ACC is controlled by Stowers Institute)

Negative

• None.

Insights

Securities Analyst

TL;DR: A sub-5% passive stake disclosed; ownership is sizable but not control-oriented.

The report shows combined beneficial ownership of 2,952,214 shares (4.8%), with 2,838,388 shares subject to sole voting power. For most investors this represents a meaningful institutional holding but remains below the 5% threshold that often triggers heightened market or governance attention. The declaration that holdings are in the ordinary course and not intended to influence control reduces the likelihood of activist intent. The parent/subsidiary relationship between ACC and ACIM is disclosed, clarifying reporting attribution.

Corporate Governance Expert

TL;DR: Disclosure improves governance transparency; no material control implications.

The Schedule 13G amendment provides clear attribution of beneficial ownership among ACIM, ACC and the Stowers Institute, and documents voting and dispositive powers. Because the position is under 5% and the filers certify the holdings are not for the purpose of changing control, this filing is governance-relevant but not materially disruptive. The filing aids investor awareness of institutional exposure without signaling imminent board or control actions.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 6)

Northwestern Energy Group, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

668074305

(CUSIP Number)

06/30/2025

(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)

SCHEDULE 13G

CUSIP No. 668074305

1

Names of Reporting Persons

American Century Investment Management, Inc.

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 2,838,388.00
6	Shared Voting Power
7	Sole Dispositive Power 2,952,214.00
8	Shared Dispositive Power

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,952,214.00

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)

4.8 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

CUSIP No. 668074305

1

Names of Reporting Persons

American Century Companies, Inc.

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 2,838,388.00
6	Shared Voting Power
7	Sole Dispositive Power 2,952,214.00
8	Shared Dispositive Power

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,952,214.00

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)

4.8 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

CUSIP No. 668074305

1

Names of Reporting Persons

Stowers Institute for Medical Research

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 2,838,388.00
6	Shared Voting Power
7	Sole Dispositive Power 2,952,214.00
8	Shared Dispositive Power

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,952,214.00

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)

4.8 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Northwestern Energy Group, Inc.
(b)	Address of issuer's principal executive offices: 3010 West 69th Street, Sioux Falls, SD, 57108
Item 2.
(a)	Name of person filing: American Century Investment Management, Inc. American Century Companies, Inc. Stowers Institute for Medical Research
(b)	Address or principal business office or, if none, residence: 4500 Main Street 9th Floor Kansas City, Missouri 64111
(c)	Citizenship: Delaware
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 668074305
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: See the response(s) to Item 9 on the attached cover page(s).
(b)	Percent of class: See the response(s) to Item 11 on the attached cover page(s).
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: See the response(s) to Item 5 on the attached cover page(s).
	(ii) Shared power to vote or to direct the vote: See the response(s) to Item 6 on the attached cover page(s).
	(iii) Sole power to dispose or to direct the disposition of: See the response(s) to Item 7 on the attached cover page(s).
	(iv) Shared power to dispose or to direct the disposition of: See the response(s) to Item 8 on the attached cover page(s).
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
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. Various persons, including the investment companies and separate institutional investor accounts that American Century Investment Management, Inc. ("ACIM") serves as investment adviser, have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the securities that are the subject of this schedule. Except as may be otherwise indicated if this is a joint filing, not more than 5% of the class of securities that is the subject of this schedule is owned by any one client advised by ACIM.
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. This Item identifies each subsidiary of American Century Companies, Inc. ("ACC"), which is controlled by the Stowers Institute for Medical Research, that is a beneficial owner of securities that are subject of this schedule (the "Subject Securities"). American Century Investment Management, Inc. ("ACIM") is a wholly-owned subsidiary of ACC and an investment adviser registered under Section 203 of the Investment Advisers Act of 1940.
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. 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.

American Century Investment Management, Inc.

Signature:	American Century Investment Management, Inc.
Name/Title:	/s/ John Pak / Senior Vice President
Date:	08/14/2025

American Century Companies, Inc.

Signature:	American Century Companies, Inc.
Name/Title:	/s/ John Pak / Senior Vice President
Date:	08/14/2025

Stowers Institute for Medical Research

Signature:	Stowers Institute for Medical Research
Name/Title:	/s/ Joselyn Verschelden / Authorized Signer
Date:	08/14/2025

Exhibit Information

EXHIBIT Each of the undersigned hereby agrees and consents to the execution and joint filing on its behalf by American Century Investment Management, Inc. of this Schedule 13G respecting the beneficial ownership of the securities which are the subject of this schedule. Dated this 14th day of August, 2025. AMERICAN CENTURY INVESTMENT MANAGEMENT, INC. ("ACIM") AMERICAN CENTURY COMPANIES, INC. ("ACC") By: __/s/ John Pak_____________ John Pak Senior Vice President, ACIM and ACC STOWERS INSTITUTE FOR MEDICAL RESEARCH, solely in its capacity as control entity of ACC By: __/s/ Joselyn Verschelden_______ Joselyn Verschelden Authorized Signer

FAQ

How many Northwestern Energy Group (NWE) shares do American Century and affiliates report owning?

The filers report beneficial ownership of 2,952,214 shares, representing 4.8% of NWE's common stock.

What voting and dispositive powers are reported in the NWE Schedule 13G/A?

The filing reports sole voting power over 2,838,388 shares and sole dispositive power over 2,952,214 shares.

Are the reported NWE shares held to influence control of the company?

No. The filers certify the securities are held in the ordinary course of business and were not acquired to change or influence control of the issuer.

Which entities are parties to this Schedule 13G/A for NWE?

The filing is by American Century Investment Management, Inc., American Century Companies, Inc., and the Stowers Institute for Medical Research.

How are the reporting entities related in the NWE filing?

The filing states ACIM is a wholly-owned subsidiary of ACC, and ACC is controlled by the Stowers Institute, explaining attribution of the reported holdings.