United States
Securities and Exchange Commission
Washington, D.C. 20549
FORM 6-K
Report of Foreign Private Issuer
Pursuant to Rule 13a-16 or 15d-16
of the
Securities Exchange Act of 1934
For the month of
September 2026
Vale S.A.
Praia de Botafogo nº 186, 18º andar,
Botafogo
22250-145 Rio de Janeiro, RJ, Brazil
(Address of principal executive office)
(Indicate by check mark whether the registrant files
or will file annual reports under cover of Form 20-F or Form 40-F.)
(Check One)
Form 20-F x Form 40-F ¨
Ticker code: CVRDA6 Rio de Janeiro, September 29th, 2025 Participating Debentures Report 1H25 Vale S.A. (“Vale”) will pay,
on September 30th, 2026, R$ 512,161,695.81 (R$ 700,458,853.73 in 2H25), equivalent to R$ 1.712064114 per participating debenture (R$ 2.341507529
in 2H25), related to the total premium for the period between January 1st and June 30th, 2026 (1H26). The financial settlement will occur
on October 1st, 2026. The total premium refers to: (i) 1.80% of the net revenues from the sale of iron ore products, in the terms of the
Debenture Deed; (ii) 1.25% of the net revenues from the sale of copper concentrate from the Sossego mine. Participating Debentures Premium
R$ 1H26 2H25 Premium on iron ore 613,758,711.77 875,537,269.98 Premium on copper concentrates 51,479,304.19 34,276,684.66 Premium on disposal
of mining rights — — Premium for the period (A) 665,238,015.95 909,813,954.64 Number of debentures under the Debenture Deed
(B) 388,559,056 388,559,056 Premium per participating debenture (C) = (A)/(B)1 1.712064114 2.341507529 Outstanding participating debentures
(D)2 299,148,666 299,148,666 Total Premium to be paid (E) = (D) x (C) 512,161,695.81 700,458,853.73 1 For the calculation of the premium
per participating debenture (unit value), as determined by the Debenture Deed, the premium for the period must be divided into equal fractions
corresponding to 1/388,559,056. For more information, please refer to the Report Preparation Basis chapter of this report. 2 Number of
debentures remaining after the settlement, by the Company, of 89,410,390 participating debentures from its 6th issuance (“Debentures”),
which adhered to the Optional Acquisition Offer in 2025. For more information about the Optional Acquisition Offer, click here. Premium
of participating debentures R$/participating debenture – 1H20 to 1H26 Income tax will be levied on the amounts to be paid to the
debenture holders, as income from fixed-income investments, in accordance with the applicable tax rate based on the beneficiary’s
specific tax status, except in cases where the beneficiary is legally exempt or subject to a different tax treatment, upon proper and
sufficient documentation. - 1 - 1.27 2.76 3.20 2.88 1.84 1.64 1.38 1.97 1.36 1.96 1.54 2.34 1.71 1H20 2H20 1H21 2H21 1H22 2H22 1H23 2H23
1H24 2H24 1H25 2H25 1H26 Rio de Janeiro, September 29th, 2026 Participating Debentures Report 1H26 Annual premium of participating debentures
Period Per debenture (R$) Total amount (R$) 2013 0.341 132,642,793.33 2014 0.732 284,859,604.30 2015 0.594 230,899,093.47 2016 1.043 405,149,990.84
2017 1.270 493,550,875.87 2018 1.654 642,842,084.48 2019 2.316 900,017,354.07 2020 4.034 1,567,329,193.88 2021 6.085 2,364,227,640.18
2022 3.482 1,352,853,305.02 2023 3.348 1,301,108,280.31 2024 3.312 1,286,907,197.85 2025 3.881 1,298,799,987.96 1H26 1.712 512,161,695.81
- 2 - 1- Basis of preparation This report has been prepared from data derived from our internal controls over financial reporting and
from data recorded in our financial systems, using the same data used to prepare our consolidated financial statements. The numbers presented
in this Participating Debentures Report 1H26 ("Report") and those found in other reports published by Vale S.A. and/or its subsidiaries
may or may not present differences. This is because different reporting frameworks have specific data requirements. Functional and presentation
currency All information contained in this report is measured using the currency of the main economic environment in which the Issuer
operates (“Functional Currency”), which is the Brazilian real (“R$” or “Reais”). Financial information
originating in a currency other than R$ is converted into Reais at the exchange rate of the transaction date or the average monthly exchange
rate, as applicable. Accounting Policy - Premium on Participating Debentures Participating debentures are financial liabilities measured
at fair value through profit or loss based on the market approach, representing the amount that would be paid for the acquisition of these
securities at the measurement date and, therefore, also implicitly includes the remuneration to the debenture holder. To calculate the
fair value of the liability, the Company uses the weighted average price of trades in the secondary market for the last month of the period.
The holders of participating debentures are entitled to receive semi-annual payments equivalent to a determined percentage of the revenue
less value-added tax, transportation fees, and insurance expenses related to the trading of products derived from these mineral resources
("Premium"). The premium must be divided into equal fractions corresponding to 1/388,559,056 of the total premium to be paid per debenture,
and these fractions will not be altered in the event of (i) acquisition of debentures by the issuer (with maintenance of such debentures
in the issuer's treasury), or (ii) cancellation of debentures held in the issuer's treasury, or (iii) acquisition of debentures by companies
controlled by the issuer, according to the criteria and parameters summarized below and described in the issuance deed. The Premium Payment
is due with respect to the Mining Rights, and is calculated based on the following percentages of the Net Revenue from the sale of certain
Products for certain Designated Areas: - 3 - Notes to the Selected Information Expressed In Brazilian Reais, except where otherwise indicated
• 1.8% for iron ore Products from certain Designated Areas in the North of Brazil and in the State of Minas Gerais and Mato Grosso
do Sul, as described in the Debenture Deed, subject to the achievement of certain triggers described in the Debenture Deed; • 2.5%
for gold or copper Products or byproducts produced in certain Designated Areas described in the Debenture Deed, subject to the beginning
of sales of Products for some of these Designated Areas or the achievement of certain triggers for other Designated Areas, as described
in the Debenture Deed; and • 1.0% for other Products or byproducts produced in certain Designated Areas, as described in the Debenture
Deed, subject to the achievement of certain triggers described in the Debenture Deed. Premium Payment is also due in the following cases:
i. Sale of to the Mining Rights: 1.0% of the sale price, net of sales taxes, in the case of a sale of a Mining Right. After the disposition
of a Mining Right, such Mining Right will cease to compose the calculation basis of the Premium Payment; and ii. Leasing of Mining Rights:
In the event that any of the Mining Rights is explored by third parties under lease agreements, the Premium Payment calculated under the
Debenture Deed will be entirely due by the Company or its Controlled Companies as if the lease had not been contracted for the purpose
of the Debenture Deed. The Premium Payment due is paid semi-annually on March 31 and September 30 of each calendar year. Any payment date
that falls on a bank or commercial holiday will be processed on the following working day. Mining Rights Premium The Premium is due in
relation to the Mining Rights and is calculated as follows: - 4 - Iron ore Premium on iron ore R$ million 1H26 2H25 1H25 2H24 1H24 Northern
System's net sales revenues 24,305.62 36,527.28 26,643.45 38,213.53 28,393.43 Southeastern System's net sales revenues 9,792.08 12,113.68
5,193.45 — — Net sales revenues 34,097.71 48,640.96 31,836.90 38,213.53 28,393.43 % basis for calculation 1.8 % 1.8 % 1.8
% 1.8 % 1.8 % Premium on iron ore (R$ million) 613.76 875.54 573.06 687.84 511.08 In 1H26, sales of iron ore totaled 129.4 Mt (148.6 Mt
in 2H25), resulting in revenues, net of maritime freight costs of R$ 51.8 billion (R$ 63.3 billion in 2H25). Iron ore sales volumes from
the Northern System in 1H26 totaled 72.2 Mt1 (96.2 Mt in 2H25), resulting in revenues, net of maritime freight costs of R$ 29.3 billion
(R$ 42.1 billion in 2H25). After applying the deductions provided in the Debenture Deed: (i) R$ 3.9 billion related to transportation
expenses (R$ 4.2 billion in 2H25); and (ii) R$ 1.1 billion related to taxes levied on sales2 (R$ 1.4 billion in 2H25), the net revenues
of the Northern System totaled R$ 24.3 billion (R$ 36.5 billion in 2H25). The premium of 1.8% for the Northern System totaled R$ 437.5
million (R$ 657.5 million in 2H25). Iron ore sales volumes from the Southeastern System in 1H26 totaled 29.3 Mt1 (33.6 Mt in 2H25), resulting
in revenues, net of maritime freight costs of R$ 11.1 billion (R$ 13.6 billion in 2H25). After applying the deductions provided in the
Debenture Deed: (i) R$ 920.7 million related to transportation expenses (R$ 1.1 billion in 2H25); and (ii) R$ 358.0 million related to
taxes levied on sales2 (R$ 444.8 million in 2H25), the net revenues of the Southeastern System totaled R$ 9.8 billion (R$ 12.1 billion
in 2H25). The premium of 1.8% for the Southeastern System totaled R$ 176.3 million (R$ 218.0 million in 2H25). - 5 - 1 Includes iron ore
transfers to pelletizing and briquetting plants. 2 Include taxes and contributions levied on sales separately, or on billing or gross
revenues from sales, as well as the financial compensation due to the Brazilian Federal Government, States and Municipalities. Notes to
the Selected Information Expressed In Brazilian Reais, except where otherwise indicated Copper concentrate Premium on copper concentrate
R$ million 1H26 2H25 1H25 2H24 1H24 Net sales revenues3 4,118.34 2,742.13 2,014.55 2,220.55 1,268.47 % basis for calculation4 1.25 % 1.25
% 1.25 % 1.25 % 1.25 % Premium on copper concentrate (R$ million) 51.48 34.28 25.18 27.76 15.86 In 1H26, sales of copper concentrate from
Sossego totaled 155 thousand metric tons (157 thousand metric tons in 2H25). The premium related to the sales of copper concentrate is
R$ 51.5 million (R$ 34.3 million in 2H25), calculated from the application of the 1.25% percentage on the net sales revenue of R$ 4.1
billion (R$ 2.7 billion in 2H25). - 6 - 3 Gross sales minus expenses with transport and insurance and taxes on sales, which include taxes
and contributions levied on sales separately, or on billing or gross revenues from sales, as well as the financial compensation due to
the Brazilian Federal Government, States and Municipalities. 4 On April 15, 1997, Vale had a 50% stake in Mineração Serra
do Sossego S.A. (Sossego). In 2001, Vale bought the remaining 50% of Sossego from Phelps Dodge do Brasil Mineração Ltda.
Hence, the percentage basis for calculating premium is 2.5%, as described in the Deed of Issue of Debentures, multiplied by Vale’s
share in the project at the time, 50%, and therefore, equal to 1.25%. Notes to the Selected Information Expressed In Brazilian Reais,
except where otherwise indicated Sales, leasing and changes in mining rights and Projects under development Sales and leasing of mining
rights In 1H26, there was 1 (one) mining right lease contained in the Debenture Deed. In 1H26, there were no sales of mining rights listed
in the Debenture Deed. In 2H25, there were no sales of mining rights listed in the Debenture Deed. Changes in mining rights In 1H26, compared
to 2H25, there was no reduction in the number of areas and hectares, maintaining the same values as the second half of 2025. In 2H25,
compared to 1H25, there was no reduction in the number of areas and hectares, maintaining the same values as the first half of 2025. The
mining rights in force on June 30th, 2026, covered by the Deed of Issue of the Debenture, amounted to 259 processes, equivalent to 1,484,710.12
hectares. The mining rights in force on December 31st, 2025, covered by the Deed of Issue of the Debenture, amounted to 259 processes,
equivalent to 1,484,710.12 hectares. The information is summarized in Annex 2 - Inventory of Mining Rights. Projects under development
On July 30th, 2026, Vale announced its 2Q26 financial results, which are available on our website: https://www.vale.com/en/announcements-results-presentations-and-reports.
- 7 - Notes to Selected Information In Brazilian Reais, except where otherwise indicated Annex 1 – Important definitions Important
definitions “Designated Areas” means the areas covered by the Mining Rights, as specified under the Debenture Deed; “Controlled
Companies” means the entities currently controlled or that may be formed or acquired by the Issuer; “Base Date” means
April 15, 1997; “Debentures” means an instrument issued in connection with the Company’s privatization process, initiated
in 1997, through the sixth issuance of such debentures, whose obligations are subordinated, unsecured and nonconvertible in stocks; “Mining
Rights” means the mining rights described in the Debenture Deed that were held by the Company or its Controlled Companies as of
the Base Date and that were not subject to exclusion under the Debenture Deed; “Issuer” means Vale S.A., a stock corporation
with head office located in Rio de Janeiro, Brazil; “Debenture Deed” means the Instrumento Particular de Escritura de Emissão
de Debêntures da Companhia Vale do Rio Doce (now Vale S.A.), dated as of June 24, 1997, registered at the 7th Registry Office (Ofício
de Registro de Imóveis) of the city of Rio de Janeiro, under number 1912, on July 3, 1997, and its amendments and supplements;
“Net Revenue” means the total of gross revenues from the sale of a Product, minus deductions solely for sales taxes and expenses
relating to transportation and insurance related to the commercialization of such Product. For purposes of this definition, “sales
taxes” consist of the taxes and contributions that apply specifically to such sales or to the revenues or gross revenue from sales,
as well as financial compensation due and payable to the Federative Republic of Brazil, and states or municipalities thereof; provided
that, with respect to mineral substances consumed or utilized in industrial processes by the Company or its Controlled Companies that
are holders of applicable mineral rights under the Debenture Deed, Net Revenue shall include the total estimated sales value of the Product,
which shall be established based on the arithmetic mean of the prices obtained by the Company or its Controlled Companies in the sale
of the same products, subject to the same deductions for sales taxes mentioned above, subject to the terms of the Debenture Deed; and
"Product" means the main mineral product considered for the purposes of the Issuance Deed, obtained after the final stage of processing,
before its industrialization. By-product means another product, obtained similarly. - 8 - Annex 2 – Inventory of Mining Rights As
of June 30th, 2026 (1H26) Block Municipality State Substance (s) Hectares Stage Carajás São Félix do Xingu, Parauapebas,
Canaã dos Carajás, Marabá, Tucumã, Curionópolis and Água Azul do Norte PA Gold, silver, copper,
iron, manganese, nickel, quartzite, granite, beryl, tin, tantalum 234,112.32 Mining concession Espinhaço Guanhães, Morro
do Pilar, Sabinópolis, Senhora do Porto and Conceição do Mato Dentro MG Gold, iron 12,738.29 Mining concession Gradaús
Rio Maria, Bannach, Cumarú do Norte, Ourilândia do Norte and Tucumã PA Tungsten, chromium, silver 26,944.91 Application
to mine Parú Jari Sul Almeirim, Mazagão and Monte Alegre AP, PA Sapropelite, sulphur, phosphate, manganese, gold, titanium
1,157,628.24 Application to carry out research Quadrilátero Ferrífero Santa Bárbara, Mariana, Nova Lima, Itabira,
Brumadinho, Ouro Preto, São Gonçalo do Rio Abaixo, Barão de Cocais, Caeté, Rio Piracicaba and Catas Altas
MG Dolomite, iron, gold, arsenic, vanadium, quartz, manganese, silver, nickel 33,246.77 Mining concession Riacho dos Machados Rio Pardo
de Minas and Riacho dos Machados MG Iron, zinc 11,100.25 Application to mine Vazante Vazante, Coromandel and Lagamar MG Zinc 8,939.34
Research permit As of December 31st, 2025 (2H25) Block Municipality State Substance (s) Hectares Stage Carajás São Félix
do Xingu, Parauapebas, Canaã dos Carajás, Marabá, Tucumã, Curionópolis and Água Azul do Norte
PA Gold, silver, copper, iron, manganese, nickel, quartzite, granite, beryl, tin, tantalum 234,112.32 Mining concession Espinhaço
Guanhães, Morro do Pilar, Sabinópolis, Senhora do Porto and Conceição do Mato Dentro MG Gold, iron 12,738.29
Mining concession Gradaús Rio Maria, Bannach, Cumarú do Norte, Ourilândia do Norte and Tucumã PA Tungsten,
chromium, silver 26,944.91 Application to mine Parú Jari Sul Almeirim, Mazagão and Monte Alegre AP, PA Sapropelite, sulphur,
phosphate, manganese, gold, titanium 1,157,628.24 Application to carry out research Quadrilátero Ferrífero Santa Bárbara,
Mariana, Nova Lima, Itabira, Brumadinho, Ouro Preto, São Gonçalo do Rio Abaixo, Barão de Cocais, Caeté, Rio
Piracicaba and Catas Altas MG Dolomite, iron, gold, arsenic, vanadium, quartz, manganese, silver, nickel 33,246.77 Mining concession Riacho
dos Machados Rio Pardo de Minas and Riacho dos Machados MG Iron, zinc 11,100.25 Application to mine Vazante Vazante, Coromandel and Lagamar
MG Zinc 8,939.34 Research permit - 9 - Any additional information about the participating debentures, including the Prospectus for Public
Trading of Participating Debentures, can be obtained on our website, www.vale.com/dividends-debts-anddebentures, from GDC Partners Serviços
Fiduciários DTVM Ltda. as fiduciary agent for the debentures, www.gdcdtvm.com.br, and from the CVM (Brazilian Securities and Exchange
Commission). - 10 - Investor Relations Vale.RI@vale.com Thiago Lofiego thiago.lofiego@vale.com Luciana Oliveti luciana.oliveti@vale.com
Pedro Terra pedro.terra@vale.com Patricia Tinoco patricia.tinoco@vale.com Internet access to the Report and Mining rights inventories
materials will be available on Vale website at www.vale.com/dividends-debts-and-debentures Further information on Vale can be found at
vale.com










Signatures
Pursuant to the requirements of the Securities
Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.
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Vale S.A.
(Registrant) |
| |
|
| |
By: |
/s/ Thiago Lofiego |
| Date: September 29, 2026 |
|
Director of Investor Relations |