Cytosorbents CEO buys 3,774 shares at $6

Cytosorbents’ CEO made an open market share purchase and now holds 100,996 split-adjusted shares including RSUs after a recent 1-for-20 reverse stock split.

Rhea-AI Filing Summary

Cytosorbents Corp (CTSO) reporting person Phillip P. Chan, Chief Executive Officer and director, purchased 3,774 shares of Common Stock in an open market transaction on September 15, 2026 at $6.00 per share, and now directly holds 100,996 shares of Common Stock, including restricted stock units.

The holdings include several tranches of RSUs that vest upon a "Change In Control" or over time under the company’s 2014 Long-Term Incentive Plan, as well as 83,782 shares of Common Stock. The share amounts reflect the 1-for-20 reverse stock split effected on September 8, 2026. No Rule 10b5-1 trading plan is reported.

Insider Trade Summary

Net Buyer: 3,774 shares

Net Buy 1 txn

Insider Chan Phillip P.

Role Chief Executive Officer

Bought 3,774 shs ($23K)

Type	Security	Shares	Price	Value
Purchase	Common Stock F1, F2, F3, F4	3,774	$6.00	$23K

Holdings After Transaction: Common Stock — 100,996 shares (Direct)

Footnotes (4)

1. F1. This transaction reported on this Form 4 reflects an open market purchase made by the Reporting Person.
2. F2. Includes: (i) the following restricted stock units ("RSUs") that will be settled into shares of Common Stock upon vesting upon a "Change In Control" of CytoSorbents Corporation (the "Issuer") as defined in the Amended and Restated CytoSorbents Corporation 2014 Long-Term Incentive Plan (the "Plan"): (a) 515 RSUs granted on March 15, 2018, (b) 935 RSUs granted on February 24, 2017, (c) 2,850 RSUs granted on June 7, 2016 and (d) 6,500 RSUs granted on April 8, 2015;
3. F3. (continued from footnote 2) (ii) 2,640 RSUs of 5,280 granted on August 8, 2025, which vest in equal parts at the first and second year anniversaries of the date of grant, subject to the Reporting Person's continued service as of the applicable vesting date, and (iii) 83,782 shares of Common Stock owned by the Reporting Person.
4. F4. Reflects the 1-for-20 reverse stock split effected by the Issuer on September 8, 2026.

Key Figures

Shares purchased: 3,774 shares Purchase price per share: $6.00 per share Shares held after transaction: 100,996 shares +4 more

7 metrics

Shares purchased 3,774 shares Open market purchase on September 15, 2026

Purchase price per share $6.00 per share Common Stock acquired on September 15, 2026

Shares held after transaction 100,996 shares Direct holdings after September 15, 2026 purchase, including RSUs

Common Stock owned 83,782 shares Portion of the CEO’s direct holdings identified as Common Stock

RSUs granted March 15, 2018 515 RSUs Settle into Common Stock upon a Change In Control under the 2014 Plan

RSUs granted August 8, 2025 (unvested portion) 2,640 RSUs Half of 5,280 RSUs, vesting over first and second anniversaries, subject to continued service

Reverse stock split ratio 1-for-20 Reverse stock split effected on September 8, 2026

Key Terms

restricted stock units ("RSUs"), Change In Control, 1-for-20 reverse stock split, Amended and Restated CytoSorbents Corporation 2014 Long-Term Incentive Plan

4 terms

restricted stock units ("RSUs") financial

"Includes: (i) the following restricted stock units ("RSUs") that will be settled"

Restricted stock units (RSUs) are a company promise to give an employee shares of stock (or cash equivalent) in the future, but only after certain conditions—usually staying with the company for a set time or hitting performance goals—are met. Investors watch RSUs because when they vest they increase the number of shares outstanding and can lead insiders to sell shares, affecting share price, company dilution and the true cost of employee pay.

Change In Control financial

"RSUs that will be settled into shares of Common Stock upon vesting upon a "Change In Control""

A "change in control" occurs when the ownership or management of a company shifts significantly, such as through a merger, acquisition, or sale of a large part of its assets. This change can impact how the company is run and may influence its future direction. For investors, it matters because it can affect the company's stability, strategy, and value, often signaling potential changes in investment risk or opportunity.

1-for-20 reverse stock split financial

"Reflects the 1-for-20 reverse stock split effected by the Issuer on September 8, 2026."

Amended and Restated CytoSorbents Corporation 2014 Long-Term Incentive Plan financial

"as defined in the Amended and Restated CytoSorbents Corporation 2014 Long-Term Incentive Plan"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did CTSO’s CEO report on this Form 4?

Phillip P. Chan, CEO and director of Cytosorbents Corp, purchased 3,774 shares of Common Stock in an open market transaction on September 15, 2026 at $6.00 per share, as reported in this Form 4.

How many CTSO shares does the CEO hold after this transaction?

After the September 15, 2026 purchase, Phillip P. Chan directly holds 100,996 shares of Cytosorbents Corp Common Stock, including multiple tranches of restricted stock units (RSUs) and 83,782 shares of Common Stock.

Were CTSO shares acquired under a Rule 10b5-1 trading plan?

No. The filing indicates the Rule 10b5-1 checkbox is not selected and a footnote states this transaction reflects an open market purchase made by the reporting person, with no Rule 10b5-1 plan reported.

What RSU awards are included in the CEO’s CTSO holdings?

The CEO’s holdings include RSUs that will settle into Common Stock, including 515 RSUs (March 15, 2018 grant), 935 RSUs (February 24, 2017), 2,850 RSUs (June 7, 2016), 6,500 RSUs (April 8, 2015), and 2,640 RSUs from an August 8, 2025 grant.

How do the CTSO RSUs vest for the CEO?

Certain RSUs vest upon a "Change In Control" of Cytosorbents Corporation as defined in the Amended and Restated Cytosorbents Corporation 2014 Long-Term Incentive Plan, while 2,640 RSUs from an August 8, 2025 grant vest in equal parts on the first and second anniversaries of the grant date, subject to continued service.

Did a reverse stock split affect the reported CTSO share numbers?

Yes. A footnote states the reported holdings reflect the 1-for-20 reverse stock split effected by Cytosorbents Corporation on September 8, 2026, so all share amounts in the filing are split-adjusted.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 09/16/2026 - 05:31 PM Accepted by SEC EDGAR 09/16/2026 - 05:30 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^*

Chan Phillip P.

(Last) (First) (Middle)

C/O CYTOSORBENTS CORPORATION

305 COLLEGE ROAD EAST

(Street)

PRINCETON NEW JERSEY 08540

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Cytosorbents Corp [ CTSO ]

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)
09/15/2026

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	09/15/2026		P		3,774(1)	A	$6	100,996(2)(3)(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. This transaction reported on this Form 4 reflects an open market purchase made by the Reporting Person.

2. Includes: (i) the following restricted stock units ("RSUs") that will be settled into shares of Common Stock upon vesting upon a "Change In Control" of CytoSorbents Corporation (the "Issuer") as defined in the Amended and Restated CytoSorbents Corporation 2014 Long-Term Incentive Plan (the "Plan"): (a) 515 RSUs granted on March 15, 2018, (b) 935 RSUs granted on February 24, 2017, (c) 2,850 RSUs granted on June 7, 2016 and (d) 6,500 RSUs granted on April 8, 2015;

3. (continued from footnote 2) (ii) 2,640 RSUs of 5,280 granted on August 8, 2025, which vest in equal parts at the first and second year anniversaries of the date of grant, subject to the Reporting Person's continued service as of the applicable vesting date, and (iii) 83,782 shares of Common Stock owned by the Reporting Person.

4. Reflects the 1-for-20 reverse stock split effected by the Issuer on September 8, 2026.

	/s/ Phillip P. Chan	09/16/2026
	** 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.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)