Exhibit 4.4


 


Execution
Version


 


 


FOURTH SUPPLEMENTAL INDENTURE (as defined herein)
(this “Fourth Supplemental Indenture”), dated as of September 22, 2021, between Macquarie Infrastructure Holdings,
LLC, a Delaware limited liability company (“MIH”), and Wells Fargo Bank, National Association, as trustee under the Indenture
referred to below (the “Trustee”).


 


WITNESSETH:


 


WHEREAS, the predecessor to MIH, Macquarie Infrastructure
Corporation, a Delaware corporation (“MIC Corp” or the “Company”), has heretofore executed and delivered
to the Trustee a Senior Debt Securities Indenture dated July 15, 2014 (the “Base Indenture”), a Second Supplemental
Indenture to the Base Indenture dated as of May 21, 2015 (the “Second Supplemental Indenture”) and a Third Supplemental
Indenture to the Base Indenture, dated as of October 13, 2016 (the “ Third Supplemental Indenture,” and together
with the Base Indenture and the Second Supplemental Indenture, the “Indenture”), providing for the issuance of its
2.00% Convertible Senior Notes due 2023 (the “Notes”);


 


WHEREAS,
On September 22, 2021, pursuant to an agreement and plan of merger, dated as of March 30, 2021 (the “Merger
Agreement”) by and among MIC Corp, MIH, a wholly-owned subsidiary of MIC Corp and Plum Merger Sub, Inc., a wholly-owned
subsidiary of MIH (“Merger Sub”), Merger Sub merged with and into MIC Corp, with MIC Corp surviving the merger as a
wholly-owned subsidiary of MIH (the “Merger”);


 


WHEREAS, at the effective time of the Merger (the
 “Effective Time”) MIC Corp’s common stock, par value $0.001 per share (the “Common Stock”)
will be converted into MIH’s common units (the “Common Units”), and stock certificates representing MIC Corp
Common Stock immediately prior to the Merger will be deemed to represent MIH’s Common Units without an exchange of certificates;


 


WHEREAS, Section 5.02(a) of the Third
Supplemental Indenture provides, among other things, that the Company may merge with or into another Person; provided that, among
other things, the Person formed by any merger with or into the Company (if other than the Company) assumes by a supplemental indenture
all of the obligations of the Company under the Notes and the Indenture;


 


WHEREAS, Section 8.07 of the Third Supplemental
Indenture provides that, in connection with, among other things, any consolidation, merger or combination involving the Company, as a
result of which Common Stock would be converted into, or exchanged for, stock, other securities, other property or assets (including cash
or any combination thereof) (any such event, a “Merger Event”) with respect to or in exchange for such Common Stock, then
the Company shall execute with the Trustee a supplemental indenture providing that the right to convert each $1,000 principal amount of
Notes shall be changed into a right to convert such principal amount of Notes for the kind and amount of shares of stock, other securities
or other property or assets (including cash or any combination thereof) receivable upon such Merger Event by a holder of a number of shares
of Common Stock issuable upon conversion of such Notes immediately prior to such Merger Event;


 






     


     


    

 


WHEREAS, immediately prior to the Effective Time,
each $1,000 principal amount of Notes was convertible into approximately 12.6572 shares of Common Stock;


 


WHEREAS, Section 7.02 of the Third Supplemental
Indenture provides, among other things, that the Indenture and Notes may be amended or supplemented without the consent of any Holder
to provide for the assumption of the Company’s obligations to Holders and to provide for conversion rights in the event of a merger
or consolidation of the Company;


 


WHEREAS, MIH desires and has requested that the
Trustee join in the execution of this Supplemental Indenture;


 


WHEREAS, MIH has heretofore delivered or is delivering
contemporaneously herewith to the Trustee the Officers’ Certificate and the Opinion of Counsel described in Section 1.02 of
the Base Indenture and Section 5.02(a) and 8.07(b) of the Third Supplemental Indenture; and


 


WHEREAS, all other acts and proceedings required
by applicable law and the Indenture necessary to authorize the execution and delivery of this Fourth Supplemental Indenture and to make
this Fourth Supplemental Indenture a valid and binding agreement for the purposes expressed herein, in accordance with its terms, have
been complied with or have been duly done or performed.


 


NOW, THEREFORE, in consideration of the foregoing
and notwithstanding any provision of the Indenture which, absent this Fourth Supplemental Indenture, might operate to limit such action,
the parties hereto, intending to be legally bound hereby, agree as follows:


 


Article 1


 


ASSUMPTION OF OBLIGATIONS


 


Section 1.1.
In accordance with the terms and conditions of the Indenture, MIH hereby assumes the due and punctual payment of the principal of, premium,
if any, and interest, if any, on the Notes, and the due and punctual performance and observance of all other covenants, conditions and
other obligations contained in the Indenture and the Notes on the part of MIC Corp to be performed or observed. MIC Corp is hereby discharged
from all of its obligations under the Indenture and the Notes.


 


Section 1.2.
MIH shall succeed to, and be substituted for, and may exercise every right and power of, MIC Corp under the Indenture and the Notes, with
the same effect as if MIH had been named as “the Company” therein.


 


Article 2


 


CONVERSION


 


Section 2.01. Settlement
Upon Conversion. In accordance with Section 7.02(a) of the Third Supplemental Indenture, from and after the date of
this Fourth Supplemental Indenture, the right to convert each $1,000 principal amount of Notes into Common Stock is hereby changed, into
a right to convert such $1,000 principal amount of Notes into Common Units, calculated so that a holder will be entitled to receive a
number of Common Units equal to the number of shares of Common Stock such holder would have been entitled to receive immediately prior
to the Merger. The provisions of the Indenture, as modified herein, shall continue to apply, mutatis mutandis, to the Holders’
right to convert each Note into the Common Units. Without limiting the foregoing, (A) MIH shall continue to have the right
to determine the form of consideration to be paid or delivered, as the case may be, upon conversion of Notes in accordance with Section 8.02
of the Third Supplemental Indenture and (B) (i) any amount payable in cash upon conversion of the Notes in accordance with Section 8.02
shall continue to be payable in cash, (ii) any shares of Common Stock that the Company would have been required to deliver upon conversion
of the Notes in accordance with ‎Section 8.02 shall instead be deliverable in Common Units and (iii) the Daily VWAP
shall be calculated based on the value of a Common Unit.


 






     


     


    

 


Section 2.02. Effectiveness. This
Fourth Supplemental Indenture will become effective and operative and binding upon each of MIH, the Trustee and the Holders as of the
Effective Time.


 


Article 3


 


MISCELLANEOUS PROVISIONS


 


Section 3.01. Capitalized Terms. Capitalized
terms used herein without definition shall have the meanings assigned to them in the Indenture.


 


Section 3.02. Indenture Remains in Full
Force and Effect. Except as supplemented hereby, all provisions of the Indenture shall remain in full force and effect.


 


Section 3.03. Governing Law. The
laws of the State of New York shall govern this Fourth Supplemental Indenture.


 


Section 3.04. Headings, Etc. The
titles and headings of the articles and sections of this Fourth Supplemental Indenture have been inserted for convenience of reference
only, are not to be considered a part hereof, and shall in no way modify or restrict any of the terms or provisions hereof.


 


Section 3.05. Separability. In
case any provision in the Indenture, as modified by this Fourth Supplemental Indenture, or in the Notes shall be invalid, illegal or unenforceable,
the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby.


 


Section 3.06. Execution in Counterparts. This
Fourth Supplemental Indenture may be executed in any number of counterparts, each of which shall be an original, but such counterparts
shall together constitute but one and the same instrument.


 


[Signature Page Follows]


 






     


     


    

 


IN WITNESS WHEREOF, the parties hereto have caused
this Fourth Supplemental Indenture to be duly executed as of the date first above written.


 


	 	MACQUARIE INFRASTRUCTURE HOLDINGS, LLC
	 	 	 
	 	By:	/s/ Christopher Frost
	 	Name:	Christopher Frost
	 	Title:	Chief Executive Officer 
	 	 	 
	 	 	 
	 	By:	/s/ Nick O’Neil
	 	Name:	Nick O’Neil
	 	Title:	Chief Financial Officer 
	 	 
	 	WELLS FARGO BANK, NATIONAL ASSOCIATION
 as Trustee
	 	 	 
	 	By:	/s/ Corey J. Dahlstrand
	 	Name:	Corey J. Dahlstrand
	 	Title:	Corporate Trust Officer



 


[Signature Page to
Fourth Supplemental Indenture]