SEC FORM 4

SEC FORM 4 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

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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^*

Ponessa Sara

(Last)

(First)

(Middle)

C/O SUITE 12, GATEWAY HUB

SHANNON AIRPORT HOUSE

(Street)

SHANNON

V14 E370

(City)

(State)

(Zip)

2. Issuer Name and Ticker or Trading Symbol
Arcadium Lithium plc [ ALTM ]

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

	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	General Counsel, VP & Sec

3. Date of Earliest Transaction (Month/Day/Year)
03/06/2025

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

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

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

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Ordinary Shares	03/06/2025		D		93,547	D	⁽¹⁾	0	D
Ordinary Shares	03/06/2025		D		153,346	D	⁽²⁾	0	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Option (Right to Buy)	$4.95	03/06/2025		D			149,215	03/06/2027	03/06/2034	Ordinary Shares	149,215	⁽³⁾	0	D
Stock Option (Right to Buy)	$7.07	03/06/2025		D			64,160	10/10/2021	10/10/2028	Ordinary Shares	64,160	⁽³⁾	0	D
Stock Option (Right to Buy)	$7.07	03/06/2025		D			64,160	10/10/2028	10/10/2028	Ordinary Shares	64,160	⁽³⁾	0	D
Stock Option (Right to Buy)	$9.7	03/06/2025		D			29,358	02/22/2026	02/22/2033	Ordinary Shares	29,358	⁽³⁾	0	D
Stock Option (Right to Buy)	$8.74	03/06/2025		D			27,887	02/23/2025	02/23/2032	Ordinary Shares	27,887	⁽³⁾	0	D
Stock Option (Right to Buy)	$8.46	03/06/2025		D			85,935	02/22/2024	02/22/2031	Ordinary Shares	85,935	⁽³⁾	0	D

Explanation of Responses:

1. Represents shares of common stock of Aracdium Lithium plc ("Arcadium") disposed of pursuant to the Transaction Agreement, dated October 9, 2024, by and among Arcadium, Rio Tinto Western Holdings Limited ("Parent") and Rio Tinto BM Subsidiary Limited ("Buyers") (the "Transaction Agreement"). Pursuant to the Transaction Agreement, at the effective time of the transaction contemplated thereby (the "Effective Time"), each share of Arcadium common stock held by the reporting person was converted automatically into the right to receive $5.85 per share in cash (the "Consideration").

2. Pursuant to the Transaction Agreement, at the Effective Time, each Arcadium restricted stock units ("Arcadium RSU") held by the reporting person and granted under the Arcadium Omnibus Incentive Plan was canceled in exchange for restricted stock units with respect to a number ofordinary shares of either Rio Tinto plc or Rio Tinto Limited ("Listed Shares") of equivalent value and with the same terms and conditions as applied to such Arcadium RSU immediately prior to the Effective Time ("Rio Tinto RSUs"). The number of Listed Shares subject to such Rio Tinto RSUs equals one multiplied by an exchange ratio of 0.0920493627351811, which equals the quotient obtained by dividing (i) the Consideration by (ii) the average volume weighted average price per ordinary share of theapplicable Listed Share for the 30 consecutive trading day period ending on the last trading day preceding the Effective Time (the "Equity Award ConversionRatio").

3. Pursuant to the Transaction Agreement, at the Effective Time, each award of Arcadium stock options ("Arcadium Options") held by the reporting person and granted under the Arcadium Omnibus Incentive Plan was canceled in exchange for an award of stock options with respect to a number of Listed Shares of equivalent value and with the same terms and conditions as applied to such stock options immediately prior to the Effective Time ("Rio Tinto Options"). The number of Listed Shares subject to each such Rio Tinto Options equals the number of shares of Arcadium common stock subject to the corresponding Arcadium Options immediately prior to the Effective Time multiplied by the Equity Award Conversion Ratio. The exercise price of each such Rio Tinto Option equals the exercise price of the corresponding Arcadium Options divided by the Equity Award Conversion Ratio.

	/s/ Sara Ponessa	03/06/2025
	** 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).
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