One Stop Systems CEO forfeits 17,242 shares for taxes

OSS’s CEO reported two Form 4 tax-withholding share forfeitures tied to RSU vesting, not open-market sales.

Rhea-AI Filing Summary

ONE STOP SYSTEMS, INC. (OSS) reported that Chief Executive Officer and director Michael Knowles disposed of shares in two transactions classified as payments of tax liability by delivering or withholding securities. On August 7, 2026 and August 15, 2026, a total of 17,242 shares of common stock were forfeited upon conversion of vested restricted stock units to cover tax withholdings, using the market price at each forfeiture. After these events, Mr. Knowles continued to hold substantial unvested restricted stock units that remain subject to vesting conditions.

Insider Trade Summary

Tax Withholding: 17,242 shares

Tax Withholding 2 txns

Insider KNOWLES MICHAEL

Role Chief Executive Officer

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock F3, F4	8,621	$13.61	$117K
Tax Withholding	Common Stock F1, F2	8,621	$13.32	$115K

Holdings After Transaction: Common Stock — 590,141 shares (Direct)

Footnotes (4)

1. F1. The Reporting Person forfeited 8,621 shares of common stock upon conversion of an aggregate 21,908 vested and outstanding restricted stock units into shares of common stock to cover tax withholdings, using the market price of the issuer's common stock at the time of forfeiture. These restricted stock units were part of the grant reported in Table I of the Form 4 filed by the Reporting Person with the Securities and Exchange Commission on February 7, 2025.
2. F2. Includes 311,403 unvested restricted stock units held by the Reporting Person, all of which remain subject to certain vesting conditions.
3. F3. The Reporting Person forfeited 8,621 shares of common stock upon conversion of an aggregate 21,908 vested and outstanding restricted stock units into shares of common stock to cover tax withholdings, using the market price of the issuer's common stock at the time of forfeiture. These restricted stock units were part of the grant reported in Table I of the Form 4 filed by the Reporting Person with the Securities and Exchange Commission on July 1, 2024.
4. F4. Includes 289,495 unvested restricted stock units held by the Reporting Person, all of which remain subject to certain vesting conditions.

Key Figures

Shares forfeited for tax withholdings (total): 17,242 shares Shares forfeited for tax withholdings per transaction: 8,621 shares Price used for tax-withholding forfeiture on August 7, 2026: $13.32 per share +4 more

7 metrics

Shares forfeited for tax withholdings (total) 17,242 shares Code F tax-withholding dispositions on August 7, 2026 and August 15, 2026

Shares forfeited for tax withholdings per transaction 8,621 shares Each of the two code F transactions

Price used for tax-withholding forfeiture on August 7, 2026 $13.32 per share Common stock used to cover tax withholdings

Price used for tax-withholding forfeiture on August 15, 2026 $13.61 per share Common stock used to cover tax withholdings

RSUs vested in each event 21,908 restricted stock units Aggregate vested and outstanding RSUs converted before each forfeiture

Unvested RSUs after August 7, 2026 event 311,403 restricted stock units Held by the reporting person, subject to vesting conditions

Unvested RSUs after August 15, 2026 event 289,495 restricted stock units Held by the reporting person, subject to vesting conditions

Key Terms

restricted stock units, tax withholdings, forfeited, vested and outstanding

4 terms

restricted stock units financial

"conversion of an aggregate 21,908 vested and outstanding restricted stock units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

tax withholdings financial

"shares of common stock ... to cover tax withholdings, using the market price"

forfeited financial

"The Reporting Person forfeited 8,621 shares of common stock upon conversion"

vested and outstanding financial

"conversion of an aggregate 21,908 vested and outstanding restricted stock units"

FAQ

What did OSS CEO Michael Knowles report on this Form 4 for OSS?

He reported two tax-withholding dispositions of common stock on August 7, 2026 and August 15, 2026, where shares were forfeited upon RSU vesting to cover tax liabilities using the market price at each forfeiture.

How many OSS (OSS) shares were forfeited for taxes in these transactions?

An aggregate of 17,242 shares of ONE STOP SYSTEMS, INC. common stock were forfeited for tax withholdings, consisting of 8,621 shares on August 7, 2026 and 8,621 shares on August 15, 2026.

Were the OSS Form 4 transactions open-market sales or part of a 10b5-1 plan?

The transactions are coded as F, described as payment of tax liability by delivering or withholding securities, not as open-market sales. The filing’s Rule 10b5-1 checkbox is not affirmatively marked for a trading plan.

What RSU vesting activity underlies the OSS CEO’s August 7, 2026 transaction?

On August 7, 2026 the reporting person forfeited 8,621 shares upon conversion of an aggregate 21,908 vested and outstanding restricted stock units into common shares to cover tax withholdings, relating to a grant previously reported on February 7, 2025.

What RSU vesting activity underlies the OSS CEO’s August 15, 2026 transaction?

On August 15, 2026 he forfeited 8,621 shares upon conversion of an aggregate 21,908 vested and outstanding restricted stock units into common shares to cover tax withholdings, relating to a grant previously reported on July 1, 2024.

How many unvested RSUs related to OSS does the CEO still hold after these events?

Footnotes state that following the August 7, 2026 event he held 311,403 unvested RSUs, and following the August 15, 2026 event he held 289,495 unvested RSUs, all subject to vesting conditions.

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Available on EDGAR 09/04/2026 - 12:33 PM Accepted by SEC EDGAR 09/04/2026 - 12:33 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

KNOWLES MICHAEL

(Last) (First) (Middle)

2235 ENTERPRISE STREET, SUITE 110

(Street)

ESCONDIDO CALIFORNIA 92029

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
ONE STOP SYSTEMS, INC. [ OSS ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Executive Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/07/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/07/2026		F		8,621(1)	D	$13.32	598,762(2)	D
Common Stock	08/15/2026		F		8,621(3)	D	$13.61	590,141(4)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. The Reporting Person forfeited 8,621 shares of common stock upon conversion of an aggregate 21,908 vested and outstanding restricted stock units into shares of common stock to cover tax withholdings, using the market price of the issuer's common stock at the time of forfeiture. These restricted stock units were part of the grant reported in Table I of the Form 4 filed by the Reporting Person with the Securities and Exchange Commission on February 7, 2025.

2. Includes 311,403 unvested restricted stock units held by the Reporting Person, all of which remain subject to certain vesting conditions.

3. The Reporting Person forfeited 8,621 shares of common stock upon conversion of an aggregate 21,908 vested and outstanding restricted stock units into shares of common stock to cover tax withholdings, using the market price of the issuer's common stock at the time of forfeiture. These restricted stock units were part of the grant reported in Table I of the Form 4 filed by the Reporting Person with the Securities and Exchange Commission on July 1, 2024.

4. Includes 289,495 unvested restricted stock units held by the Reporting Person, all of which remain subject to certain vesting conditions.

	/s/ Michael Knowles	09/04/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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* Form 4: SEC 1474 (03-26)