Exhibit 4.26.1

SUPPLEMENTAL INDENTURE NO. 1

SUPPLEMENTAL INDENTURE No. 1, dated as
of September 17, 2012, among CEMEX, S.A.B. de C.V., a sociedad anónima bursátil de capital variable organized under the laws of the United Mexican States (the Issuer), the existing guarantors under the
Indenture (as defined below) listed on Schedule I hereto (collectively, the Existing Guarantors), the additional guarantors listed on Schedule II hereto (collectively, the New Guarantors and,
together with the Existing Guarantors, the Note Guarantors) and The Bank of New York Mellon, as trustee (the Trustee).

W I T N E S S E T H:

WHEREAS, the Issuer, the Existing Guarantors and the Trustee previously have entered into an indenture, dated as of April 5,
2011 (the Indenture), providing for the issuance of the Issuers Floating Rate Senior Secured Notes due 2015 (the Notes);

WHEREAS, Section 9.1(a)(i) of the Indenture provides that the Issuer, the Existing Guarantors and the Trustee may enter into a supplemental indenture without notice to or consent of any
Holder to cure any ambiguity, omission, defect or inconsistency in the Indenture;

WHEREAS, the Issuer desires to amend
and supplement the Indenture as provided in Article II hereof to cure certain ambiguities, omissions, defects and inconsistencies in the Indenture;

WHEREAS, Section 9.1(a)(iv) of the Indenture provides that the Issuer, the Existing Guarantors and the Trustee may enter into a supplemental indenture without notice to or consent of
any Holder to add guarantees with respect to the Notes;

WHEREAS, the Issuer desires to amend and supplement the
Indenture as provided in Article III hereof to provide for the guarantee by the New Guarantors of the Issuers Obligations under the Notes and the Indenture on the terms and conditions set forth herein;

WHEREAS, the Issuer and the Note Guarantors are authorized to execute and deliver this Supplemental Indenture No. 1;

WHEREAS, the Issuer has requested that the Trustee join in the execution of this Supplemental Indenture No. 1
pursuant to Section 9.6 of the Indenture; and

WHEREAS, all things necessary to make this
Supplemental Indenture No. 1 a valid agreement of the parties and a valid supplement to the Indenture have been done.



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NOW, THEREFORE, for and in consideration of the premises and the mutual covenants
contained herein and in the Indenture and for other good and valuable consideration, the receipt and sufficiency of which are herein acknowledged, the Issuer, the Note Guarantors and the Trustee hereby agree, for the benefit of all Holders, as
follows:

ARTICLE I

DEFINITIONS

Section 1.01 Defined Terms. All capitalized terms used
but not defined herein shall have the meanings ascribed to such terms in the Indenture, as supplemented and amended hereby. All definitions in the Indenture shall be read in a manner consistent with the terms of this Supplemental Indenture
No. 1.

ARTICLE II

AMENDMENTS

Section 2.01 Definitions. Section 1.1 of the
Indenture is amended as follows:

(a) The definition of Note Guarantors is amended in its entirety to read as
follows:

Note Guarantors means (i) each of the Issuers Restricted Subsidiaries that executes
this Indenture as a Note Guarantor or an Additional Note Guarantor and (ii) each of the Issuers Restricted Subsidiaries that in the future executes a supplemental indenture in which such Restricted Subsidiary agrees to be bound by the
terms of this Indenture as a Note Guarantor, and their respective successors and assigns; provided that any Person constituting a Note Guarantor as described above shall cease to constitute a Note Guarantor when its respective Note Guarantee is
released in accordance with the terms of this Indenture.

(b) Clause (3) of the definition of Capital
Stock is amended in its entirety to read as follows:

(3) any warrants, rights or options to purchase any of the
instruments or interests referred to in clause (1) or (2) above, but excluding any Indebtedness exchangeable into such equity interest in existence on the Issue Date or Incurred pursuant to Section 3.9.



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ARTICLE III

NOTE GUARANTEES

Section 3.01 Agreement to Guarantee. Subject to the
limitations set out in Section 3.02 and 3.03, each New Guarantor hereby agrees, jointly and severally with the other Note Guarantors, irrevocably, fully and unconditionally, to guarantee the Obligations under the Indenture and the
Notes on the terms and subject to the conditions set forth in Article X of the Indenture and to be bound by (and shall be entitled to the benefits of) all other applicable provisions of the Indenture as a Note Guarantor.

Section 3.02 French Guarantee Limitation.

(a) The obligations of any New Guarantor incorporated in France (a French Note Guarantor) are subject to the limitations set out in this Section 3.02.

(b) The obligations and liabilities of any French Note Guarantor under the Indenture and the Notes, and in particular under this
Article III and Article X of the Indenture, shall not include any obligation or liability which, if incurred, would constitute the provision of financial assistance within the meaning of article L.225-216 of the French Commercial Code
and/or would constitute a misuse of corporate assets within the meaning of article(s) L. 241-3 or L. 242-6 of the French Commercial Code or any other law or regulations having the same effect, as interpreted by French courts.

(c) The obligations and liabilities of any French Note Guarantor under this Article III and Article X of the Indenture for
the Issuers obligations under the Indenture and the Notes shall be limited, at any time, to an amount equal to the aggregate of all amounts made available under the Notes and the Indenture to the Issuer to the extent directly or indirectly
on-lent to such French Note Guarantor and/or its direct and indirect Subsidiaries under intercompany loan agreements (excluding, for the avoidance of doubt, any cash-pooling arrangements or other cash management agreements, provided that the
proceeds of the Notes shall not be used, in whole or in part, to finance, directly or indirectly, such cash pooling arrangements or other cash management agreements) and outstanding at the date a payment is to be made by such French Note
Guarantor under this Article III and Article X of the Indenture, it being specified that any payment made by a French Note Guarantor under this Article III and Article X of the Indenture in respect of the obligations of
the Issuer shall reduce pro tanto the outstanding amount of the intercompany loans due by such French Note Guarantor or its relevant direct or indirect Subsidiary under the intercompany loan agreements referred to above and that any repayment
of the intercompany loans by the French Note Guarantor or its relevant direct or indirect Subsidiary shall reduce pro tantothe amount payable by the French Note Guarantor under this Article III and Article X of the Indenture.

(d) It is acknowledged that no French Note Guarantor is acting jointly and severally with the other Note Guarantors and no
French Guarantor shall therefore be considered as co-débiteur solidaire as to its obligations pursuant to the guarantee given pursuant to this Article III and Article X of the Indenture.



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Section 3.03 Swiss Guarantee Limitation.

(a) The obligations of any New Guarantor incorporated in Switzerland (a Swiss Note Guarantor) are subject to the
limitations set out in this Section 3.03.

(b) The obligations and liabilities of a Swiss Note Guarantor under the
Indenture, the Notes or any other agreement, and in particular under this Article III and Article X of the Indenture, in relation to the obligations, undertakings, indemnities or liabilities of a Note Guarantor other than that Swiss
Note Guarantor or any of its fully owned and controlled subsidiaries (the Restricted Obligations) shall not include any obligation or liability which, if incurred, would constitute the provision of financial assistance not
permitted under the laws of Switzerland then in force and/or would constitute a misuse of corporate assets under Swiss law as interpreted by Swiss courts and shall be limited to the amount of that Swiss Note Guarantors Free Reserves Available
for Distribution at the time payment is requested, provided that such limitation is a requirement under applicable law (including any case law) at that point in time and that such limitation shall not free the Swiss Note Guarantor from its
obligations in excess thereof, but merely postpone the performance date until such time as performance is permitted notwithstanding such limitation.

(c) For the purpose of this clause, Free Reserves Available for Distribution means an amount equal to the maximal amount in which the relevant Swiss Note Guarantor can make a dividend payment
to its shareholder(s) (being the balance sheet profit and any freely disposable reserves available for this purpose, in each case in accordance with applicable Swiss law).

(d) As soon as possible after having been requested to discharge a Restricted Obligation, the Swiss Note Guarantor shall, if it cannot discharge the full amount of the Restricted Obligations, provide the
Trustee with an interim statutory balance sheet audited by the statutory auditors of the Swiss Note Guarantor setting out the Free Reserves Available for Distribution and, immediately thereafter, pay the amount corresponding to the Free Reserves
Available for Distribution to the Trustee (save to the extent provided below).

(e) In respect of the Restricted Obligations,
the Swiss Note Guarantor shall:



| | (i) | if and to the extent required by applicable law in force at the relevant time:
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| | (A) | subject to any applicable double taxation treaties, deduct Swiss withholding tax at the rate of 35 percent (or such other rate as is in force at that time) from any
payment made by it;
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| | (B) | pay any such deduction to the Swiss Federal Tax Administration; and
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| | (C) | notify and provide evidence to the Trustee that the Swiss withholding tax has been paid to the Swiss Federal Tax Administration;
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| | (ii) | to the extent such deduction is made, not be required to make a gross-up, indemnify or otherwise hold harmless the Trustee or the Holders for the deduction of the Swiss
withholding tax notwithstanding anything to the contrary contained in the Indenture, the Notes or any other agreement, unless grossing up is permitted under the laws of Switzerland then in force and provided that this should not in any way limit any
obligations of any non-Swiss Note Guarantors under the Indenture, the Notes or any other agreement to indemnify the Trustee or the Holders in respect of the deduction of the Swiss withholding tax. The Swiss Note Guarantor shall use all reasonable
efforts to procure that any person which is entitled to a full or partial refund of any Swiss withholding tax paid pursuant to paragraph (a) above will, as soon as possible after the deduction of the Swiss withholding tax: (y) request a
refund of the Swiss withholding tax under any applicable law (including double taxation treaties) and (z) pay to the Trustee upon receipt any amount so refunded.
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(f) The Swiss Note Guarantor will take, and cause to be taken, all and any other action, including, without limitation, the passing of
any shareholders resolutions to approve any payment or other performance under the Indenture and the Notes and the receipt of any confirmations from the Swiss Note Guarantors auditors, whether following a request to discharge a
Restricted Obligation or which may be required as a matter of mandatory Swiss law in force at the time it is required to make a payment or perform other obligations under the Indenture, the Notes or any other agreement in order to allow a prompt
payment or performance of other obligations under the Indenture or the Notes.

(g) If the enforcement of the Restricted
Obligations would be limited due to the effects referred to in this Section 3.03 and if any asset of the Swiss Note Guarantor has a book value that is less than its market value (an Undervalued Asset), the Swiss Note
Guarantor shall, to the extent permitted by applicable law and its accounting standards (i) write up the book value of such Undervalued Asset such that its balance sheet reflects a book value that is equal to the market value of such
Undervalued Asset, and (ii) make reasonable efforts to realize the Undervalued Asset for a sum which is at least equal to the market value of such asset. Without prejudice to the rights of the Trustee and the Holders under the Indenture, the
Notes or any other agreement, the Swiss Note Guarantor will only be required to realize an Undervalued Asset if such asset is not necessary for the Swiss Note Guarantors business (nicht betriebsnotwendig).



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ARTICLE IV

MISCELLANEOUS

Section 4.01. Effect of This Supplemental Indenture
No. 1.This Supplemental Indenture No. 1 supplements the Indenture and shall be a part, and subject to all the terms, thereof. The Indenture, as supplemented and amended by this Supplemental Indenture No. 1, is in all
respects ratified and confirmed, and the Indenture and this Supplemental Indenture No. 1 shall be read, taken and construed as one and the same instrument. All provisions included in this Supplemental Indenture No. 1 supersede any
conflicting provisions included in the Indenture, unless not permitted by law.

Section 4.02 Governing Law. This
Supplemental Indenture No. 1 shall be governed by, and construed in accordance with, the laws of the State of New York.

Section 4.03 Effect of Headings. The section headings herein are for convenience only and shall not affect the construction
of this Supplemental Indenture No. 1.

Section 4.04 Counterparts. The parties may sign any number of copies
of this Supplemental Indenture No. 1. Each signed copy shall be an original, but all of them shall represent the same agreement.

Section 4.05 The Trustee. The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture No. 1 or for or in
respect of the recitals contained herein, all of which are made solely by the Issuer and the Note Guarantors. In entering into this Supplemental Indenture No. 1, the Trustee shall be entitled to the benefit of every provision of the Indenture
relating to the conduct or affecting the liability or affording protection to the Trustee whether or not elsewhere herein so provided. The Issuer and the Note Guarantors expressly reaffirm and confirm their obligations to indemnify the Trustee in
connection with the Indenture and all the actions contemplated hereby, all in accordance with the terms of the Indenture.

[SIGNATURE PAGE TO FOLLOW IMMEDIATELY]



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IN WITNESS WHEREOF, the parties have caused this Supplemental Indenture No. 1 to be
duly executed as of the date first written above.



CEMEX, S.A.B. de C.V., as IssuerBy:

/s/ José Antonio González FloresName:

José Antonio González FloresTitle:

Attorney-In-FactCEMEX México, S.A. de C.V., as Note GuarantorBy:

/s/ José Antonio González FloresName:

José Antonio González FloresTitle:

Attorney-In-FactCEMEX España, S.A., as Note GuarantorBy:

/s/ Héctor José Vela DibName:

Héctor José Vela DibTitle:

Attorney-In-FactNew Sunward Holding B.V., as Additional Note GuarantorBy:

/s/ Héctor José Vela DibName:

Héctor José Vela DibTitle:

Attorney-In-FactCEMEX Research Group AG, as Note GuarantorBy:

/s/ Francisco Javier García Ruiz de MoralesName:

Francisco Javier García Ruiz de MoralesTitle:

Attorney-In-Fact


[Signature page to Supplemental Indenture No. 1 (Floating Rate Senior Secured Notes due 2015)]



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CEMEX Shipping B.V., as Note GuarantorBy:

/s/ Francisco Javier García Ruiz de MoralesName:

Francisco Javier García Ruiz de MoralesTitle:

Attorney-In-FactCEMEX Asia B.V., as Note GuarantorBy:

/s/ Francisco Javier García Ruiz de MoralesName:

Francisco Javier García Ruiz de MoralesTitle:

Attorney-In-FactCEMEX France Gestion (S.A.S.), as Note GuarantorBy:

/s/ Francisco Javier García Ruiz de MoralesName:

Francisco Javier García Ruiz de MoralesTitle:

Attorney-In-FactCEMEX UK, as Note GuarantorBy:

/s/ Francisco Javier García Ruiz de MoralesName:

Francisco Javier García Ruiz de MoralesTitle:

Attorney-In-FactCEMEX Egyptian Investments B.V., as Note GuarantorBy:

/s/ Francisco Javier García Ruiz de MoralesName:

Francisco Javier García Ruiz de MoralesTitle:

Attorney-In-Fact


[Signature page to Supplemental Indenture No. 1 (Floating Rate Senior Secured Notes due 2015)]



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THE BANK OF NEW YORK MELLON, as TrusteeBy:

/s/ Catherine F. DonohueName:

Catherine F. DonohueTitle:

Vice President


[Signature page to Supplemental Indenture No. 1 (Floating Rate Senior Secured Notes due 2015)]



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SCHEDULE I

EXISTING GUARANTORS



| | 1. | CEMEX México, S.A. de C.V.
| | -- | --------------------------



| | 2. | CEMEX España, S.A.
| | -- | ------------------



| | 3. | New Sunward Holding B.V.
| | -- | ------------------------



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SCHEDULE II

NEW GUARANTORS



| | 1. | CEMEX Research Group AG
| | -- | -----------------------



| | 2. | CEMEX Shipping B.V.
| | -- | -------------------



| | 3. | CEMEX Asia B.V.
| | -- | ---------------



| | 4. | CEMEX France Gestion (S.A.S.)
| | -- | -----------------------------



| | 5. | CEMEX UK
| | -- | --------



| | 6. | CEMEX Egyptian Investments B.V.
| | -- | -------------------------------