Weichai Group Files 13D/A: Disposes 263K PSIX Shares at ~$80–89.8

Rhea-AI Filing Summary

Weichai America Corp., together with Weichai Power Co., Ltd. and Shandong Heavy Industry Group Co., Ltd., filed Amendment No. 8 to their Schedule 13D for Power Solutions International, Inc. (PSIX) to report open-market sales of Common Stock under Rule 144. From August 18–21, 2025, Weichai America sold a total of 263,006 shares, reducing the Reporting Persons' combined beneficial ownership to 10,948,835 shares, or 47.5% of the outstanding common stock based on 23,029,846 shares outstanding as of July 31, 2025. The filing lists daily dispositions and weighted average prices per share ranging from about $80.00 to $89.83. The amendment states no other transactions occurred since the prior Schedule 13D.

Positive

• Transparent disclosure of daily share dispositions and weighted average prices supports regulatory compliance
• Continues to hold substantial stake at 47.5%, preserving significant influence over the issuer

Negative

• Aggregate ownership fell by over 1% after the sale of 263,006 shares, modestly reducing voting power
• No clarified intent about future transactions or strategic plans following the reduction, creating uncertainty for governance expectations

Insights

Securities Analyst

TL;DR: A roughly 1.1% stake reduction via Rule 144 sales, transparent reporting but still leaves the group as a near-majority holder.

The Reporting Persons executed orderly open-market disposals of 263,006 shares over four trading days, with weighted average prices per day disclosed. The reduction lowered their aggregate stake to 47.5%, beneath majority control but maintaining substantial influence. The clear breakdown of shares sold and prices supports market transparency and regulator compliance; however, the sales modestly reduce the group's voting leverage. No other material transactions or changes were disclosed in this amendment.

Corporate Governance Specialist

TL;DR: Filing shows compliant disclosure of dilutive sales but raises governance questions about future control intentions.

The amendment appropriately updates Schedule 13D to reflect disposals under Rule 144 and provides daily volume and weighted average price detail. While the combined ownership remains significant at 47.5%, the reported sale decreased their previously disclosed percentage by more than 1%, which could influence governance dynamics and shareholder voting outcomes. The document contains no statement of changed intent or future plans, leaving uncertainty about whether further reductions or strategic actions are planned.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 8)

POWER SOLUTIONS INTERNATIONAL, INC.

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class of Securities)

73933G202

(CUSIP Number)

Weichai America Corp.
Attn: Jinguang Liu (aka Jin Liu), 3100 Golf Road
Rolling Meadows, IL, 60008
(855-922-9001)

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

08/21/2025

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

SCHEDULE 13D

CUSIP No. 73933G202

1

Name of reporting person

Weichai America Corp.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

ILLINOIS

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 10,948,835.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 10,948,835.00

11

Aggregate amount beneficially owned by each reporting person

10,948,835.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

47.5 %

14

Type of Reporting Person (See Instructions)

CO

Comment for Type of Reporting Person:

1. The number of shares beneficially owned represents 10,948,835 shares of Common Stock held by the Reporting Persons. 2. The beneficial ownership percentage is calculated in accordance with Rule 13d-3 under the Securities Exchange Act of 1934, as amended, based upon information from the Issuer's Quarterly Report on Form 10-Q filed on August 8, 2025 that, as of July 31, 2025, there were 23,029,846 shares of Common Stock outstanding.

SCHEDULE 13D

CUSIP No. 73933G202

1

Name of reporting person

Weichai Power Co., Ltd.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

CHINA

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 10,948,835.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 10,948,835.00

11

Aggregate amount beneficially owned by each reporting person

10,948,835.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

47.5 %

14

Type of Reporting Person (See Instructions)

CO

Comment for Type of Reporting Person:

1. The number of shares beneficially owned represents 10,948,835 shares of Common Stock held by the Reporting Persons. 2. The beneficial ownership percentage is calculated in accordance with Rule 13d-3 under the Securities Exchange Act of 1934, as amended, based upon information from the Issuer's Quarterly Report on Form 10-Q filed on August 8, 2025 that, as of July 31, 2025, there were 23,029,846 shares of Common Stock outstanding.

SCHEDULE 13D

CUSIP No. 73933G202

1

Name of reporting person

Shandong Heavy Industry Group Co., Ltd.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

CHINA

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 10,948,835.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 10,948,835.00

11

Aggregate amount beneficially owned by each reporting person

10,948,835.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

47.5 %

14

Type of Reporting Person (See Instructions)

CO

Comment for Type of Reporting Person:

1. The number of shares beneficially owned represents 10,948,835 shares of Common Stock held by the Reporting Persons. 2. The beneficial ownership percentage is calculated in accordance with Rule 13d-3 under the Securities Exchange Act of 1934, as amended, based upon information from the Issuer's Quarterly Report on Form 10-Q filed on August 8, 2025 that, as of July 31, 2025, there were 23,029,846 shares of Common Stock outstanding.

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, par value $0.001 per share
(b)	Name of Issuer: POWER SOLUTIONS INTERNATIONAL, INC.
(c)	Address of Issuer's Principal Executive Offices: 201 Mittel Drive, Wood Dale, ILLINOIS , 60191.
Item 1 Comment: This constitutes Amendment No. 8 ("Amendment No. 8") to the Schedule 13D relating to the shares of Common Stock of Power Solutions International, Inc. (the "Issuer") as filed with the SEC on April 7, 2017, as amended by Amendment No. 1, Amendment No. 2, Amendment No. 3, Amendment No. 4, Amendment No. 5, Amendment No. 6 and Amendment No. 7 as filed with the SEC on August 10, 2017, December 5, 2017, August 31, 2018, October 3, 2018, April 26, 2019, August 15, 2025 and August 19, 2025, respectively (as so amended, the "Schedule 13D"), by Weichai America Corp. ("Weichai America"), Weichai Power Co., Ltd. ("Weichai Power"), and Shandong Heavy Industry Group Co., Ltd. ("SHIG") (each of Weichai America, Weichai Power, and SHIG a "Reporting Person" and collectively the "Reporting Persons"). Capitalized terms used in this Amendment No. 8 without being defined herein have the respective meanings given to them in the Schedule 13D. This Amendment No. 8 is being filed by the Reporting Persons to report the open market sales by Weichai America of an aggregate of 263,006 shares of the Issuer's Common Stock pursuant to Rule 144 under the Securities Act of 1933, as amended ("Rule 144"), through a broker-dealer from August 18, 2025 to August 21, 2025 (the "Sales"). The Sales resulted in a decrease of over one percent (1%) in the aggregate percentage ownership reported by the Reporting Persons in Amendment No. 7 to the Schedule 13D. Except as specifically amended by this Amendment No. 8, this Schedule 13D is not modified or revised in any material way.
Item 4.	Purpose of Transaction
	Item 4 is hereby amended and supplemented by adding the following: On August 8, 2025, Weichai Amercia filed a notice with the SEC on Form 144 relating to the proposed sale of up to 1,150,000 shares of Common Stock in accordance with Rule 144. From August 18, 2025 to August 21, 2025, the Reporting Persons sold an aggregate of 263,006 shares of Common Stock in a series of open-market transactions through a broker-dealer.
Item 5.	Interest in Securities of the Issuer
(a)	Item 5(a) is hereby amended and restated as set forth below: The Reporting Persons may be deemed to beneficially own the shares of Common Stock of the Issuer as set forth on Exhibit Q hereto.
(b)	Item 5(b) is hereby amended and restated as set forth below: The Reporting Persons may be deemed to beneficially own the shares of Common Stock of the Issuer as set forth on Exhibit Q hereto.
(c)	Item 5(c) is hereby amended and restated as set forth below: In connection with the Sales, Weichai America sold 263,006 shares of Common Stock in a series of open-market transactions, through a broker-dealer, pursuant to Rule 144. Details by date, listing the number of shares of Common Stock disposed of and the weighted average price per share, are provided below. August 18, 2025 - Shares Disposed of: 125,220 - Weighted Average Price Per Share: $85.0118 (multiple transactions at prices ranging from $80.00 to $89.83 inclusive) August 19, 2025 - Shares Disposed of: 79,670 - Weighted Average Price Per Share: $81.0820 (multiple transactions at prices ranging from $80.00 to $84.65 inclusive) August 20, 2025 - Shares Disposed of: 15,802 - Weighted Average Price Per Share: $80.4970 (multiple transactions at prices ranging from $80.00 to $81.00 inclusive) August 21, 2025 - Shares Disposed of: 42,314 - Weighted Average Price Per Share: $82.2664 (multiple transactions at prices ranging from $80.00 to $83.64 inclusive) The Reporting Persons undertake to provide, upon request by the staff of the SEC, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate price for each of the above transactions. Except as set forth above, none of the Reporting Persons has effected any transaction in shares of Common Stock since the most recent filing of Schedule 13D.
Item 7.	Material to be Filed as Exhibits.
	Exhibit Q - Beneficial Ownership of the Reporting Persons in the Securities of Power Solutions International, Inc. Exhibit R - Powers of Attorney (Weichai Power Co., Ltd.), incorporated by reference to Exhibit 24.1 to the Form 4 filed by Reporting Persons with the Securities and Exchange Commission on August 14, 2025. Exhibit S - Power of Attorney (Shandong Heavy Industry Group Co., Ltd.), incorporated by reference to Exhibit 24.2 to the Form 4 filed by Reporting Persons with the Securities and Exchange Commission on August 14, 2025.

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.

Weichai America Corp.

Signature:	/s/ Jinguang Liu (aka Jin Liu)
Name/Title:	Jinguang Liu (aka Jin Liu), Chief Financial Officer
Date:	08/25/2025

Weichai Power Co., Ltd.

Signature:	/s/ Chenglong Sun
Name/Title:	Chenglong Sun, Authorized Representative
Date:	08/25/2025

Shandong Heavy Industry Group Co., Ltd.

Signature:	/s/ Chenglong Sun
Name/Title:	Chenglong Sun, Authorized Representative
Date:	08/25/2025

FAQ

What did Weichai America report in the Schedule 13D/A for PSIX?

The filing reports that Weichai America sold 263,006 shares of Power Solutions International common stock under Rule 144 from August 18–21, 2025.

How much of PSIX does the reporting group now own?

After the sales, the Reporting Persons beneficially own 10,948,835 shares, representing 47.5% of PSIX based on 23,029,846 shares outstanding as of July 31, 2025.

What were the prices for the shares sold by Weichai America?

Daily weighted average prices ranged approximately from $80.50 to $85.01, with reported transaction price ranges between $80.00 and $89.83.

Was the Schedule 13D/A filed for compliance or a change in intent?

The amendment reports open-market sales and states the Sales decreased ownership by over 1%; it does not state any change in overall purpose or future intent beyond the reported transactions.

Who signed the filing for the Reporting Persons?

The amendment is signed by Jinguang Liu for Weichai America and Chenglong Sun as authorized representative for Weichai Power and SHIG.