ZeroStack: Alexander Pack reports 8.6% passive stake
The reported stake is attributed through shared voting and investment authority over four investment vehicles, with percentages based on 22,276,008 shares outstanding.
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ZeroStack Corp. (ZSTK) Schedule 13G reports Alexander Pack, managing member of Hack VC Management, LLC and sole manager of three general partners, as beneficially owning 1,920,360 shares, or 8.6%, through shared voting and investment authority. The shares are held directly by 0G Segregated Portfolio (80,015), Hack Seed Fund II LP (1,680,315), Hack VC 2021 LP (80,015), and Hack VF 2022 LP (80,015). The reporting persons disclaim group status. The ownership percentages are based on 22,276,008 shares outstanding as of September 30, 2026.
Key Figures
Beneficial ownership:1,920,360 sharesOwnership percentage:8.6%Shares outstanding:22,276,008 shares+2 more
5 metrics
Beneficial ownership1,920,360 sharesAlexander Pack; shared voting and dispositive power
Ownership percentage8.6%Alexander Pack; based on 22,276,008 shares outstanding as of September 30, 2026
Shares outstanding22,276,008 sharesAs of September 30, 2026
Direct holding1,680,315 sharesHack Seed Fund II LP
Direct holding80,015 sharesEach of 0G Segregated Portfolio, Hack VC 2021 LP, and Hack VF 2022 LP
Key Terms
beneficially owned, Shared Voting Power, Shared Dispositive Power
3 terms
beneficially ownedregulatory
"Amount beneficially owned"
Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.
Shared Voting Powerregulatory
"Shared Voting Power 1,920,360.00"
Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.
Shared Dispositive Powerregulatory
"Shared Dispositive Power 1,920,360.00"
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
How many ZSTK shares does Alexander Pack beneficially own?
Alexander Pack is reported as beneficially owning 1,920,360 ZeroStack shares, or 8.6%. The filing bases ownership percentages on 22,276,008 shares outstanding as of September 30, 2026.
Which funds directly hold the shares reported for ZSTK?
Hack Seed Fund II LP held 1,680,315 shares directly; 0G Segregated Portfolio, Hack VC 2021 LP, and Hack VF 2022 LP each held 80,015 shares directly. Pack shares voting and investment authority over all four holdings.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
ZeroStack Corp.
(Name of Issuer)
Common Stock, $0.0001 par value per share
(Title of Class of Securities)
98957E106
(CUSIP Number)
07/20/2026
(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):
98957E106
1
Names of Reporting Persons
Hack VC Management, 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
80,015.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
80,015.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
80,015.00
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)
0.4 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP Number(s):
98957E106
1
Names of Reporting Persons
0G Segregated Portfolio, a designated Segregated Portfolio of Sybil Ventures SPC 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
VIRGIN ISLANDS, BRITISH
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
80,015.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
80,015.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
80,015.00
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)
0.4 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP Number(s):
98957E106
1
Names of Reporting Persons
Hack Seed Fund II 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
CAYMAN ISLANDS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
1,680,315.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,680,315.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,680,315.00
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)
7.5 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP Number(s):
98957E106
1
Names of Reporting Persons
Hack Seed Fund II 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
1,680,315.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,680,315.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,680,315.00
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)
7.5 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP Number(s):
98957E106
1
Names of Reporting Persons
Sybil Capital Fund I 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
CAYMAN ISLANDS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
80,015.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
80,015.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
80,015.00
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)
0.4 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP Number(s):
98957E106
1
Names of Reporting Persons
Hack VC 2021 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
80,015.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
80,015.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
80,015.00
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)
0.4 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP Number(s):
98957E106
1
Names of Reporting Persons
Hack VF 2022 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
CAYMAN ISLANDS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
80,015.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
80,015.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
80,015.00
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)
0.4 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP Number(s):
98957E106
1
Names of Reporting Persons
Hack VF 2022 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
80,015.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
80,015.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
80,015.00
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)
0.4 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP Number(s):
98957E106
1
Names of Reporting Persons
Alexander Pack
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
1,920,360.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,920,360.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,920,360.00
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)
8.6 %
12
Type of Reporting Person (See Instructions)
IN
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
ZeroStack Corp.
(b)
Address of issuer's principal executive offices:
2626 Cole Ave, Suite 300, Dallas, TX, 75204.
Item 2.
(a)
Name of person filing:
The names of the persons filing this report (collectively, the "Reporting Persons") are:
Hack VC Management, LLC ("Hack Management")
0G Segregated Portfolio, a designated Segregated Portfolio of Sybil Ventures SPC Ltd. ("0G Segregated Portfolio")
Hack Seed Fund II GP LLC ("Hack Seed II GP")
Hack Seed Fund II LP ("Hack Seed II")
Sybil Capital Fund I GP LLC ("Hack VC 2021 GP")
Hack VC 2021 LP ("Hack VC 2021")
Hack VF 2022 GP LLC ("Hack VF 2022 GP")
Hack VF 2022 LP ("Hack VF 2022")
Alexander Pack ("Pack")
The Reporting Persons expressly disclaim status as a "group" for purposes of this Schedule 13G.
(b)
Address or principal business office or, if none, residence:
251 Lytton Ave, Suite 200
Palo Alto, CA 94301.
(c)
Citizenship:
Hack Management Delaware
0G Segregated Portfolio British Virgin Islands
Hack Seed II GP Cayman Islands
Hack Seed II Cayman Islands
Hack VC 2021 GP Cayman Islands
Hack VC 2021 Cayman Islands
Hack VF 2022 GP Cayman Islands
Hack VF 2022 Cayman Islands
Pack United States
(d)
Title of class of securities:
Common Stock, $0.0001 par value per share
(e)
CUSIP Number(s):
98957E106
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:
Row 9 of each Reporting Person's cover page to this Schedule 13G sets forth the aggregate number of shares of common stock of the Issuer beneficially owned by such Reporting Person and is incorporated by reference.
The Reporting Persons' ownership of the Issuer's securities consists of (i) 80,015 shares of common stock directly held by 0G Segregated Portfolio; (ii) 1,680,315 shares of common stock directly held by Hack Seed II; (iii) 80,015 shares of common stock directly held by Hack VC 2021; and (iv) 80,015 shares of common stock directly held by Hack VF 2022.
Hack Management is the manager of the 0G Segregated Portfolio and shares voting and investment authority over the securities held by the 0G Segregated Portfolio.
Hack Seed II GP is the general partner of Hack Seed II and shares voting and investment authority over the securities held by Hack Seed II.
Hack VC 2021 GP is the general partner of Hack VC 2021 and shares voting and investment authority over the securities held by Hack VC 2021.
Hack VF 2022 GP is the general partner of Hack VF 2022 and shares voting and investment authority over the securities held by Hack VF 2022.
Pack is the managing member of Hack Management and the sole manager of each of Hack Seed II GP, Hack VC 2021 GP and Hack VF 2022 GP and shares voting and investment authority over the securities held by each of 0G Segregated Portfolio, Hack Seed II, Hack VC 2021 and Hack VF 2022.
(b)
Percent of class:
Row 11 of each Reporting Person's cover page to this Schedule 13G sets forth the percentages of the shares of common stock of the Issuer beneficially owned by such Reporting Person and is incorporated by reference. The percentage set forth in each row 11 is based upon 22,276,008 shares of common stock outstanding as of September 30, 2026, as reported by the Issuer to the Reporting Persons.
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
Row 5 of each Reporting Person's cover page to this Schedule 13G sets forth the sole power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person and is incorporated by reference.
(ii) Shared power to vote or to direct the vote:
Row 6 of each Reporting Person's cover page to this Schedule 13G sets forth the shared power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person and is incorporated by reference.
(iii) Sole power to dispose or to direct the disposition of:
Row 7 of each Reporting Person's cover page to this Schedule 13G sets forth the sole power to dispose or to direct the disposition of securities of the Issuer beneficially owned by such Reporting Person and is incorporated by reference.
(iv) Shared power to dispose or to direct the disposition of:
Row 8 of each Reporting Person's cover page to this Schedule 13G sets forth the shared power to dispose or to direct the disposition of securities of the Issuer beneficially owned by such Reporting Person and is incorporated by reference.
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.
Not Applicable
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.
Hack VC Management, LLC
Signature:
/s/ Daniel Bulaevsky
Name/Title:
By Daniel Bulaevsky, General Counsel
Date:
10/19/2026
0G Segregated Portfolio, a designated Segregated Portfolio of Sybil Ventures SPC Ltd.
Signature:
/s/ Daniel Bulaevsky
Name/Title:
By Hack VC Management, LLC, its Manager, By Daniel Bulaevsky, General Counsel
Date:
10/19/2026
Hack Seed Fund II GP LLC
Signature:
/s/ Daniel Bulaevsky
Name/Title:
By Daniel Bulaevsky, Authorized Signatory
Date:
10/19/2026
Hack Seed Fund II LP
Signature:
/s/ Daniel Bulaevsky
Name/Title:
By Hack Seed Fund II GP LLC, its general partner, By Daniel Bulaevsky, Authorized Signatory
Date:
10/19/2026
Sybil Capital Fund I GP LLC
Signature:
/s/ Daniel Bulaevsky
Name/Title:
By Daniel Bulaevsky, Authorized Signatory
Date:
10/19/2026
Hack VC 2021 LP
Signature:
/s/ Daniel Bulaevsky
Name/Title:
By Sybil Capital Fund I GP LLC, its general partner, By Daniel Bulaevsky, Authorized Signatory
Date:
10/19/2026
Hack VF 2022 GP LLC
Signature:
/s/ Daniel Bulaevsky
Name/Title:
By Daniel Bulaevsky, Authorized Signatory
Date:
10/19/2026
Hack VF 2022 LP
Signature:
/s/ Daniel Bulaevsky
Name/Title:
By Hack VF 2022 GP LLC, its general partner, By Daniel Bulaevsky, Authorized Signatory
