Exhibit 10.4

Accession Letter

From: Smurfit WestRock US Holdings Corporation (the Company) and Smurfit Kappa Investments Limited (the Obligors' Agent)

To: Wells Fargo Bank, National Association (the Agent)

Dated: 2 July 2024

Dear Sirs/Madams

Smurfit Kappa Treasury Unlimited Company – $5,100,000,000 Facility Agreement dated 28 June 2024 (the Agreement)

1. We refer to the Agreement. This is an Accession Letter. Terms defined in the Agreement have the same meaning in this Accession Letter unless given a different meaning in this Accession Letter.

2. This Accession Letter shall be effective on and from its date, except that the Company shall have no obligations under this letter or any other Finance Document until the Combination has been consummated. The Obligors’ Agent shall notify the Agent of the consummation of the Combination as soon as practicable thereafter.

3. Subject to paragraph 2 above, the Company agrees to become an Additional Guarantor and to be bound by the terms of the Agreement as an Additional Guarantor pursuant to Clause 28.4 (Additional Guarantors) of the Agreement.

4. The Company is a company duly incorporated under the laws of the State of Delaware, United States of America.

5. The Company's administrative details are as follows:

Address:	Beech Hill, Clonskeagh, Dublin 4,Ireland
Attention:	Emer Murnane
Email:	[     ]
Telephone:	[     ]

6. This Accession Letter and any non-contractual obligations arising out of or in connection with it are governed by English law.

7. This Accession Letter is entered into as a deed.

[Signature page follows.]

EXECUTION PAGE – Accession Letter

SIGNED for and on behalf of

SMURFIT KAPPA INVESTMENTS LIMITED

by its lawfully appointed attorney

in the presence of
and delivered as a deed	/s/ Kenneth Bowles
	Signature
/s/ Rory Carbery
Witness (Signature)
2 Grand Canal Square
Print Address
Solicitor
Witness Occupation

[Signature Page to Smurfit WestRock US Holdings Corporation Accession Letter]

SIGNED and DELIVERED as a DEED
for and on behalf of
SMURFIT WESTROCK US HOLDINGS CORPORATION
By:	/s/ Kenneth Bowles
Name:	Kenneth Bowles
Title:	Authorised Signatory

[Signature Page to Smurfit WestRock US Holdings Corporation Accession Letter]