AdvanSix Inc. ownership filing: CastleKnight Master Fund LP and affiliated CastleKnight entities, together with Weitman Capital LLC and Aaron Weitman, report beneficial ownership of 1,666,382 shares of AdvanSix common stock, representing 6.2% of the class as shown on 05/07/2026. The filing lists shared voting and shared dispositive power over these shares across the reporting entities.
Positive
None.
Negative
None.
Insights
Large passive stake disclosed with shared control.
The filing shows a 6.2% beneficial position totaling 1,666,382 shares held via CastleKnight Master Fund LP and affiliated entities as of 05/07/2026. Voting and dispositive power are reported as shared, with no sole voting or dispositive authority noted.
That structure suggests coordinated influence through fund and manager entities rather than direct individual control; subsequent filings or proxy materials may clarify whether this stake prompts engagement or voting intentions.
Disclosure clarifies ownership and entity relationships.
The report lists the exact share count (1,666,382), the percent of class (6.2%), and the CUSIP 00773T101. It names CastleKnight Fund GP LLC, CastleKnight Management entities, Weitman Capital LLC, and Aaron Weitman as reporting persons with shared voting/dispositive power.
Investor relations should note the public filing date and be prepared to address inquiries about intent; cash‑flow treatment or plans for the shares are not disclosed in the excerpt.
Key Figures
Shares beneficially owned:1,666,382 sharesPercent of class:6.2%Reporting date:05/07/2026+1 more
4 metrics
Shares beneficially owned1,666,382 sharesreported as beneficial ownership by CastleKnight entities and Aaron Weitman
Percent of class6.2%percent of AdvanSix common stock represented by the reported shares
Reporting date05/07/2026date shown near the filing header
CUSIP00773T101AdvanSix Inc. common stock CUSIP listed in the filing
A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.
Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.
shared dispositive powerregulatory
"8 | Shared Dispositive Power 1,666,382.00"
CUSIPregulatory
"Title of class of securities: Common Stock, par value $0.01 per share CUSIP Number(s): 00773T101"
A CUSIP is a nine-character alphanumeric code that uniquely identifies a U.S. or Canadian financial security—such as a stock, bond, or fund share—like a Social Security number for an investment. It matters to investors because brokers, exchanges and record-keepers use the CUSIP to match trades, track ownership, settle transactions and pull accurate records, reducing errors and ensuring money and securities go to the right place.
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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
AdvanSix Inc.
(Name of Issuer)
Common Stock, par value $0.01 per share
(Title of Class of Securities)
00773T101
(CUSIP Number)
05/07/2026
(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):
00773T101
1
Names of Reporting Persons
CastleKnight Master Fund LP
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
CAYMAN ISLANDS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
1,666,382.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,666,382.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,666,382.00
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)
PN
SCHEDULE 13G
CUSIP Number(s):
00773T101
1
Names of Reporting Persons
CastleKnight Fund GP LLC
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
0.00
6
Shared Voting Power
1,666,382.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,666,382.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,666,382.00
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)
OO
SCHEDULE 13G
CUSIP Number(s):
00773T101
1
Names of Reporting Persons
CastleKnight Management LP
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
0.00
6
Shared Voting Power
1,666,382.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,666,382.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,666,382.00
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)
IA, PN
SCHEDULE 13G
CUSIP Number(s):
00773T101
1
Names of Reporting Persons
CastleKnight Management GP LLC
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
0.00
6
Shared Voting Power
1,666,382.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,666,382.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,666,382.00
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)
OO
SCHEDULE 13G
CUSIP Number(s):
00773T101
1
Names of Reporting Persons
Weitman Capital LLC
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
NEW JERSEY
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
1,666,382.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,666,382.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,666,382.00
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)
OO
SCHEDULE 13G
CUSIP Number(s):
00773T101
1
Names of Reporting Persons
Aaron Weitman
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
UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
1,666,382.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,666,382.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,666,382.00
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, IN
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
AdvanSix Inc.
(b)
Address of issuer's principal executive offices:
300 Kimball Drive, Suite 101, Parsippany, New Jersey 07054
Item 2.
(a)
Name of person filing:
CastleKnight Master Fund LP
CastleKnight Fund GP LLC
CastleKnight Management LP
CastleKnight Management GP LLC
Weitman Capital LLC
Aaron Weitman
(b)
Address or principal business office or, if none, residence:
CastleKnight Master Fund LP
Maples Corporate Services Limited
P.O. Box 309
Ugland House
Grand Cayman KY1-1104
Cayman Islands
CastleKnight Fund GP LLC
888 Seventh Avenue, 24th Floor
New York, New York 10019
United States of America
CastleKnight Management LP
888 Seventh Avenue, 24th Floor
New York, New York 10019
United States of America
CastleKnight Management GP LLC
888 Seventh Avenue, 24th Floor
New York, New York 10019
United States of America
Weitman Capital LLC
c/o Aaron Weitman
c/o CastleKnight Management LP
888 Seventh Avenue, 24th Floor
New York, New York 10019
United States of America
Aaron Weitman
c/o CastleKnight Management LP
888 Seventh Avenue, 24th Floor
New York, New York 10019
United States of America
(c)
Citizenship:
CastleKnight Master Fund LP - Cayman Islands
CastleKnight Fund GP LLC - Delaware
CastleKnight Management LP - Delaware
CastleKnight Management GP LLC - Delaware
Weitman Capital LLC - New Jersey
Aaron Weitman - United States
(d)
Title of class of securities:
Common Stock, par value $0.01 per share
(e)
CUSIP Number(s):
00773T101
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:
CastleKnight Master Fund LP - 1,666,382
CastleKnight Fund GP LLC - 1,666,382
CastleKnight Management LP - 1,666,382
CastleKnight Management GP LLC - 1,666,382
Weitman Capital LLC - 1,666,382
Aaron Weitman - 1,666,382
(b)
Percent of class:
CastleKnight Master Fund LP - 6.2%
CastleKnight Fund GP LLC - 6.2%
CastleKnight Management LP - 6.2%
CastleKnight Management GP LLC - 6.2%
Weitman Capital LLC - 6.2%
Aaron Weitman - 6.2%
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
CastleKnight Master Fund LP - 0
CastleKnight Fund GP LLC - 0
CastleKnight Management LP - 0
CastleKnight Management GP LLC - 0
Weitman Capital LLC - 0
Aaron Weitman - 0
(ii) Shared power to vote or to direct the vote:
CastleKnight Master Fund LP - 1,666,382
CastleKnight Fund GP LLC - 1,666,382
CastleKnight Management LP - 1,666,382
CastleKnight Management GP LLC - 1,666,382
Weitman Capital LLC - 1,666,382
Aaron Weitman - 1,666,382
(iii) Sole power to dispose or to direct the disposition of:
CastleKnight Master Fund LP - 0
CastleKnight Fund GP LLC - 0
CastleKnight Management LP - 0
CastleKnight Management GP LLC - 0
Weitman Capital LLC - 0
Aaron Weitman - 0
(iv) Shared power to dispose or to direct the disposition of:
CastleKnight Master Fund LP - 1,666,382
CastleKnight Fund GP LLC - 1,666,382
CastleKnight Management LP - 1,666,382
CastleKnight Management GP LLC - 1,666,382
Weitman Capital LLC - 1,666,382
Aaron Weitman - 1,666,382
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.
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 see Exhibit B attached hereto.
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 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.
CastleKnight Master Fund LP
Signature:
By: CastleKnight Fund GP LLC, its general partner, By: Weitman Capital LLC, its managing member, /s/ Aaron Weitman
Name/Title:
Aaron Weitman, Manager
Date:
05/14/2026
CastleKnight Fund GP LLC
Signature:
By: Weitman Capital LLC, its managing member, /s/ Aaron Weitman
Name/Title:
Aaron Weitman, Manager
Date:
05/14/2026
CastleKnight Management LP
Signature:
By: CastleKnight Management GP LLC, its general partner, By: Weitman Capital LLC, its managing member, /s/ Aaron Weitman
Name/Title:
Aaron Weitman, Manager
Date:
05/14/2026
CastleKnight Management GP LLC
Signature:
By: Weitman Capital LLC, its managing member, /s/ Aaron Weitman
Name/Title:
Aaron Weitman, Manager
Date:
05/14/2026
Weitman Capital LLC
Signature:
/s/ Aaron Weitman
Name/Title:
Aaron Weitman, Manager
Date:
05/14/2026
Aaron Weitman
Signature:
/s/ Aaron Weitman
Name/Title:
Aaron Weitman
Date:
05/14/2026
Comments accompanying signature: * Each Reporting Person disclaims beneficial ownership of the reported securities except to the extent of his or its pecuniary interest therein, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.
Exhibit Information
Exhibit A - Joint Filing Agreement
Exhibit B - Control Person Identification
What stake did CastleKnight report in AdvanSix (ASIX)?
CastleKnight and affiliated entities reported beneficial ownership of 1,666,382 shares, equal to 6.2% of AdvanSix common stock as of 05/07/2026. The filing lists shared voting and shared dispositive power across the reporting entities.
Which entities and individuals are listed as reporting persons in the ASIX filing?
The filing names CastleKnight Master Fund LP, CastleKnight Fund GP LLC, CastleKnight Management LP, CastleKnight Management GP LLC, Weitman Capital LLC, and Aaron Weitman as reporting persons with shared control.
Does the Schedule 13G show who has sole voting or dispositive power?
No sole authority is reported. Each listed reporting person shows 0 shares of sole voting or sole dispositive power and 1,666,382 shares of shared voting and shared dispositive power.
What date and CUSIP are associated with this AdvanSix ownership report?
The filing references the date 05/07/2026 near the cover data and lists the CUSIP for AdvanSix common stock as 00773T101 in the disclosure.
