Inferra AI / Company / OGC / Slides
OceanaGold — OGC Corporate Presentation September 2026 (company IR deck)
OceanaGold (OGC) · 41 slides · Filed Oct 29, 2026
Every slide of this earnings presentation, with the text as published. Open the original deck ↗ · All OGC deck slides
Slide 1 — Performance,
Performance, Growth, Returns September 2026 T S X / N YS E : O G C
Slide 2 — Cautionary Statements
Cautionary Statements Cautionary Note Regarding Forward-Looking Statements This presentation contains certain “forward-looking statements” and “forward-looking information” (collectively, “forward-looking statements”) within the meaning of applicable Canadian and United States securities laws which may include, but are not limited to, statements with respect to: the future financial and operating performance of OceanaGold Corporation (“OceanaGold” or the “Company”) and its mining projects, including the Company’s planned production, cost and capital 2026 Guidance; the future price of gold, copper and silver; the development, expansion and operation of OceanaGold’s mining projects and the anticipated benefits therefrom; anticipated results and developments in the operations of OceanaGold in current and future periods; anticipated closing of the Company’s acquisition of Ausgold Limited (“Ausgold”); anticipated production levels and mine life of operations, including targeted production at Macraes to the late 2030s and at the Katanning Gold Project; estimated timing for first ore at each of Wharekirauponga and the Katanning Gold Project; the estimation, realization and classification of Mineral Reserves and Mineral Resources; costs of production; estimates of growth capital, sustaining capital, operating and exploration expenditures; estimated timing of the commissioning of the water treatment plant expansion, early works on TSF 3 and exploration drilling from underground at the Waihi North Project; estimated mine life of operations, including the Macraes Phase 4 Project (“MP4”) potentially extending mine life at Macraes to the late 2030s and other mine life extension opportunities to potentially further extend mine life at Macraes into the 2040s; the expected timing for the transition of Ledbetter at Haile to an underground mine; estimated first ore production at each of the Palomino Underground and Ledbetter Underground at Haile; timing of the development of new deposits and mines, including the Waihi North Project, MP4 and Katanning Gold Project; the advancement of organic growth projects, including Palomino Underground at Haile, the Waihi North Project and MP4; costs and timing of future exploration and drilling programs, including the Company’s site and regional exploration programs; increase in the exploration budget planned for 2026; estimated capital allocation for 2026; the availability of, and access to, labour, equipment, power, diesel, water and other inputs; timing, cost and outcome of development, construction and expansion activities; timing of filing of updated technical information and studies, including the timing for the updated technical report for Macraes and the Waihi District; the adequacy of current financial resources and cash reserves; requirements for additional capital; foreign operations and political, economic and regulatory conditions in the jurisdictions in which OceanaGold operates; expectations regarding the impacts of the U.S.-Iran international conflict on OceanaGold’s operations, including potential impacts to operating and capital costs; governmental regulation of mining operations and exploration; timing and receipt of permits, certifications, approvals and licenses under applicable legislation; the amount of and timing for share buybacks under the Company’s Normal Course Issuer Bid; the payment of dividends in future periods; estimated Free Cash Flow or FCF yield and EV EBITDA in 2026; the Company’s 2026 corporate scorecard and its sustainability-related KPIs; anticipated environmental risks; and the timing and possible outcome of pending legal proceedings, regulatory matters and other disputes. All statements in this presentation that address events or developments that OceanaGold expects to occur in the future are forward-looking statements. Forward-looking statements are statements that are not historical facts and are generally, although not always, identified by words such as “may”, “plans”, “expects”, “projects”, “is expected”, “scheduled”, “potential”, “estimates”, “forecasts”, “intends”, “targets”, “aims”, “anticipates” or “believes” or variations (including negative variations) of such words and phrases, or may be identified by statements to the effect that certain actions, events or results “may”, “could”, “would”, “should”, “might” or “will” be taken, occur or be achieved. Forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of OceanaGold to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Such risks include, among others: the risk of not achieving production estimates, forecasts or 2026 Guidance; inaccuracy of Mineral Reserves, Mineral Resources and operating and capital cost estimates; the actual results of current and future production, development and/or exploration activities; possible variations of ore grade, metallurgy or recovery rates; changes in mine plans, project parameters or assumptions as plans continue to be refined; delays in, or inability to complete, development or construction or expansion activities or to re- commence or sustain operations as planned; failures or underperformance of plant, equipment, infrastructure or processes; geotechnical risks or events, including open pit wall stability, crown pillar failure, land subsidence and tailings dam failures; scarcity in and disruption of global supply chain and/or increases in prices, including as a result of international conflicts, such as the recent and ongoing U.S.-Iran conflict; challenges associated with effective water management; environmental, health and safety and climate-related risks; risks related to community acceptance, stakeholder engagement and social licence to operate; competition for mineral properties and other growth opportunities; legal and regulatory challenges to current and future permits, certifications, approvals or licences; adverse judicial, regulatory or governmental decisions; delays in, or inability to obtain, financing or governmental approvals on acceptable terms; changes in laws, regulations, taxation regimes, regulated accounting standards or their interpretation or application; the risks associated with operating in foreign jurisdictions, including political instability, changes in policy or law, civil unrest, blockades or conflict; fluctuations in the prices of gold, copper and silver; general business, economic and market conditions (including changes in global, national or regional financial, credit, currency or securities markets); changes or developments in global, national or regional political and social conditions; fluctuations in foreign exchange rates, including the value of the U.S. dollar relative to the Canadian dollar, the New Zealand dollar or the Philippine peso; trade policies and tensions, including tariffs; inflationary pressure; labour availability, retention and turnover; accidents, labour disputes, work stoppages and other operational risks of the mining industry; limitations of insurance coverage or uninsured risks; the conclusions of economic evaluations, studies and models; information technology, artificial intelligence and cybersecurity risks; and those other factors identified and described in more detail in the section entitled “Risk Factors” contained in OceanaGold’s most recent Annual Information Form and OceanaGold’s other filings with Canadian securities regulators and the U.S. Securities and Exchange Commission (“SEC”), which are available under OceanaGold’s profile on SEDAR+ at sedarplus.ca and on EDGAR at sec.gov, respectively, and on OceanaGold’s website at oceanagold.com. The list is not exhaustive of the factors that may affect OceanaGold's forward-looking statements. Although OceanaGold believes that any forward-looking statements contained in this presentation are based on reasonable assumptions, readers cannot be assured that actual outcomes or results will be consistent with such forward-looking statements. Accordingly, readers should not place undue reliance on forward-looking statements. OceanaGold expressly disclaims any intention or obligation to update or revise any forward-looking statements whether as a result of new information, events or otherwise, except as required by applicable securities laws. Cautionary Note Regarding Non-IFRS Measures This presentation includes certain terms or performance measures commonly used in the mining industry that are not defined under IFRS, including All-In Sustaining Costs (“AISC”), Operating Cash Flow per share, EBITDA, Free Cash Flow or FCF, Free Cash Flow per share and Net Cash. Non- IFRS measures do not have any standardized meaning prescribed under IFRS, and therefore they may not be comparable to similar measures employed by other companies. OceanaGold provides these non-IFRS measures as they are used by certain investors to evaluate its performance. Accordingly, the data presented is intended to provide additional information and should not be considered in isolation or as a substitute for measures of performance prepared in accordance with IFRS and should be read in conjunction with OceanaGold’s consolidated financial statements. Readers should refer to OceanaGold’s Q4 2025 Management's Discussion & Analysis dated February 18, 2026 (“Q4 2025 MD&A”) and Q2 2026 Management's Discussion & Analysis dated August 5, 2026 (“Q2 2026 MD&A”) available on SEDAR+ at sedarplus.ca under OceanaGold’s name and OceanaGold’s website at www.oceanagold.com under the heading "Non-IFRS Financial Measures“ for a more detailed discussion of how OceanaGold calculates certain of such measures and a reconciliation of certain measures to IFRS terms. Qualified Persons Except as otherwise stated herein, each of: Mr. Greg Hollett, OceanaGold's Head of Mine Engineering, has reviewed and approved the disclosure of all scientific and technical information related to Haile operational matters; Mr. Euan Leslie, OceanaGold's Group Mining Engineer, and Mr. Knowell Madambi, OceanaGold's Manager – Technical Services & Projects, Macraes, have reviewed and approved the disclosure of all scientific and technical information related to Macraes operational matters; Messrs. Leslie and David Townsend, OceanaGold's Manager – Mining (Underground), Waihi, have reviewed and approved the disclosure of all scientific and technical information related to Waihi operational matters; Mr. Phillip Jones, OceanaGold's Head of Underground Mining, has reviewed and approved the disclosure of all scientific and technical information related to Didipio operational matters; and Mr. Keenan Jennings, OceanaGold's Executive Vice President and Chief Exploration Officer, has reviewed and approved the scientific and technical information related to exploration matters contained in this presentation. Each of Messrs. Hollett, Jennings, Jones, Leslie, Madambi and Townsend is a qualified person as defined by National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”). General Presentation Notes All AISC are net of by-product credits unless otherwise stated. All financials are denominated in U.S. dollars unless otherwise stated. 2
Slide 3 — Global Intermediate Gold and Copper Producer
Global Intermediate Gold and Copper Producer 35+ years of exploration, development and operating experience Attractive organic growth opportunities across the portfolio Mining gold for a better future 4 operating mines in attractive jurisdictions USA, New Zealand & the Philippines 1. Non-IFRS measure. See “Cautionary Statements” in this presentation. 2. Based on Mineral Resources and Mineral Reserves estimates for the year ended December 31, 2025. Mineral Resources are inclusive of Mineral Reserves. See news release dated February 18, 2026 and “Appendix” in this presentation for more information. 3 Safely and responsibly maximizing generation of Free Cash Flow1 and delivering strong returns to shareholders Total Gold Reserves of 5.8 Moz2 and M&I Resources of 8.6 Moz2
Slide 4 — Our Purpose
Our Purpose Mining gold for a better future Our Vision To be a company people trust, want to work and partner with, supply and invest in, to create value Our Values Care Respect Integrity Performance Teamwork 4
Slide 5 — Diversified Portfolio in Top Mining
5 DIDIPIO Philippines HAILE USA HEAD OFFICE Vancouver, Canada MACRAES New Zealand WAIHI New Zealand Diversified Portfolio in Top Mining Jurisdictions KATANNING 1 Western Australia 2026 Guidance: 85 – 105 koz Au 13 – 15 kt Cu • First gold expected in 2029 • +100,000 oz annual gold production 2026 Guidance: 235 – 260 koz Au TECHNICAL OFFICE Brisbane, Australia 2026 Guidance: 60 – 75 koz Au 2026 Guidance: 135 – 155 koz Au GOLD & COPPER producer 1. Subject to closing of OceanaGold’s acquisition of Ausgold. See news release titled “OceanaGold Announces Acquisition of Ausgold” dated August 17, 2026 for more information. 2. AISC is a non-IFRS measure. See “Cautionary Statements” in this presentation. 2026 Guidance 520 – 590 koz GOLD PRODUCTION 13 – 15 kt COPPER PRODUCTION $1,750 - $1,900 AISC2
Slide 6 — Leadership Team
GERARD BOND President & Chief Executive Officer MARIUS VAN NIEKERK EVP, Chief Financial Officer BHUVANESH MALHOTRA EVP, Chief Operating Officer KEENAN JENNINGS EVP, Chief Exploration Officer MICHELLE EDELSON EVP, Chief People & Technology Officer ELIZABETH THAMPY EVP, General Counsel and Company Secretary DAVID BICKERTON EVP, Chief Sustainability Officer Strong, Capable & Aligned Leadership Team 6
Slide 7 — Executing on Our Corporate Strategy
Executing on Our Corporate Strategy TACTICS 2 1 3 5 4 Safely, Responsibly & Reliably Deliver Gold Production Sustainability A Caring, Inclusive and Winning Culture Living the Vision and Values Increase Reserves & Deliver New Resources Cost Effectively Exploration Premium Rating with the Investment Community Independent Board Deliver Financial Strength and Returns Strong balance sheet Value capture programs Technical excellence Market engagement Shareholder returns Capable and well-led people Operating excellence Early-stage entry Trusted Management Low-cost capital Five pillars to increase and sustain a higher value for OceanaGold shares Project execution External opportunities Capital management discipline Risk management Develop & retain talent 7
Slide 8 — Safely, Responsibly & Reliably Deliver Gold Production
350 400 450 500 550 600 2024 Actual 2025 Actual 2026 Guidance Gold Production (koz) Safely, Responsibly & Reliably Deliver Gold Production 498 590 1 Organic, low-risk, production growth 520 489 2026 production growth is driven by Haile 1 1. See Q4 2025 MD&A for more information. Guidance is subject to annual review and change. 8
Slide 9 — Indicative Production Growth Profile
- 100 200 300 400 500 600 700 800 900 2027E 2028E 2029E 2030E 2031E 2032E 2033E 2034E Au Production (koz) Haile Didipio Waihi Macraes Macraes production target Katanning Indicative Production Growth Profile Potential for production growth to ~650,000 oz per year 9 Waihi & Waihi North Project 1. Based on the most recent NI 43-101 technical report for each of Haile, Didipio, Waihi and Macraes. See “Appendix” in this presentation for more information. 2. Based on Macraes targeted production of above 100,000 ounces per year into the late 2030s. Refer to news release dated September 9, 2026 for more information. 3. Subject to closing of OceanaGold’s acquisition of Ausgold. Katanning production is illustrative of 100,000 oz per year, with 50,000 oz in 2029E reflecting production ramp up. See news release titled “OceanaGold Announces Acquisition of Ausgold” dated August 17, 2026 for more information. Potential production profile with Katanning1,2,3 2 3 Katanning Gold Project First ore expected from Wharekirauponga UG in 2032 First ore expected from Katanning in 20293 Potential to contribute over 100,000 oz/year3 Updated technical report expected in January 2027 Evaluating continued mining of Martha UG concurrently with WKP UG and a mill expansion at Waihi to 1.2 Mtpa ~650 koz Macraes Potential to extend production to the 2040s
Slide 10 — Updated Technical Reports
Updated Technical Reports Positioned to generate substantial FCF1, based on reserves only2 HAILE MACRAES DIDIPIO 248 231 208 200 202 214 174 167 145 80 26 $1,600 $1,577 $1,573 $1,575 $1,513 $1,307 $1,519 $1,314 $1,553 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2026 NI 43-101 Technical Report 2026 Guidance2 2026 NI 43-101 Technical Report 2026 Guidance2 2026 NI 43-101 Technical Report Production (koz) AISC ($/oz)1 ✓ Expected to produce an average of 210,000 oz Au per year from 2027 to 2031 inclusive ✓ First ore from Palomino UG expected in 2028 ✓ First ore from Ledbetter UG expected in 2029 ✓ Mine life extended by 5 years, with additional open pit cutbacks at Innes Mills, Coronation, Coronation North and Golden Bar ✓ Application lodged to extend life to late 2030s ✓ Successful exploration and studies could extend into 2040s ✓ Underground ore mining rates increasing to 2.8 Mtpa by 2030 ✓ Generates significant FCF1 over the Life of Mine 95 101 101 84 82 95 90 72 89 86 73 29 $1,025 $1,361 $1,056 $1,565 $1,459 $1,193 $1,109 $1,355 $1,164 $1,144 $1,153 $1,412 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2026 Guidance2 1. FCF is a non-IFRS measure. See “Cautionary Statements” in this presentation. 2. Based on the mid-point of the Company’s 2026 Guidance. See Q4 2025 MD&A and “Appendix “ in this presentation for more information. Subject to market and operating conditions. 10 145 100 105 85 65 77 21 $2,050 $2,446 $2,253 $2,559 $2,641 $1,716 $1,309 2027 2028 2029 2030 2031 2032
Slide 11 — Central to Business
Sustainability is Central to Business Performance 27% of short-term incentive KPIs are sustainability related High importance on delivering results in a responsible way Safety of the workforce, care for the environment, positive relationships with the community Board, Management and operations aligned on sustainability deliverables 40% 23% 4% 6% 17% 10% Production Growth Culture Cost & Continuous Improvement Health & Safety Environment, Energy & Carbon 2026 Corporate Scorecard & KPI Breakdown 11
Slide 12 — A Caring, Inclusive and Winning Culture
A Caring, Inclusive and Winning Culture 2 Culture survey achieved strong employee engagement scores Strength in technical expertise and across our business Focused on creating an inclusive and respectful workplace experience for our workforce Living Our Values program celebrates outstanding role models of our Values 12
Slide 13 — Increase Resources & Reserves Cost Effectively
Increase Resources & Reserves Cost Effectively 3 Conversion of Resources to Reserves New greenfield opportunities & earn-ins Brownfield exploration to grow Resources 2026 Priorities 2025A 2026E Didipio Waihi District Macraes Haile Record exploration spend planned for 2026 $40M 1. Totals may not add due to rounding. See Q4 2025 MD&A for more information. 13 $10M $10M $10M $25M $60M1
Slide 14 — Key Catalysts
PROJECT CATALYST EXPECTED TIMING1 HAILE Palomino Underground First ore 2028 2029 MACRAES Underground mining optimization Increasing UG mining rates Commenced May 2026 Key Catalysts Attractive organic growth projects DIDIPIO Waihi North Project development Underground tunnelling Ongoing Technical Report (NI 43-101) Waihi District updated mine plan Further mine life extension 1. Expected timing subject to review and adjustments by the Company. 14 Ledbetter Underground First ore January 2027 2026 Record exploration budget Technical Report (NI 43-101) Early 2028 $10M exploration budget Drilling at depth & at True Blue 2026 Katanning Gold Project KATANNING Completion of Ausgold acquisition December 2026 WAIHI DISTRICT
Slide 15 — Deliver Financial Strength and Returns
0 14 30 2022 2023 2024 2025 2026E Deliver Financial Strength and Returns 4 Robust financial position No debt Adding Cash to the Balance Sheet Net Cash (debt) ($M)1 Returning Capital to Shareholders Dividends ($M) Buybacks ($M) (170) (77) 192 477 655 2022 2023 2024 2025 Q2 2026 up to 432 Tripled annual dividend for 2026 ($0.36 per share annually) Doubled share buybacks for 2026, up to $350M 203 1. Net Cash is a non-IFRS measure. See “Cautionary Statements” in this presentation. 15 Returned $174M via dividends & buybacks in H1 2026
Slide 16 — A Focus on Per Share Metrics
A Focus on Per Share Metrics Exploration Spend ($/share) Free Cash Flow1 ($/share) Operating Cash Flow1 ($/share) Production (oz/‘000 share) 2.0 2.0 2.0 2.2 2.4 2022 2023 2024 2025 H1 2026 Annualized 1.62 1.69 2.48 3.96 6.23 2022 2023 2024 2025 H1 2026 Annualized 0.37 0.18 1.01 2.32 3.45 2022 2023 2024 2025 H1 2026 Annualized 0.09 0.10 0.12 0.17 0.22 2022 2023 2024 2025 H1 2026 Annualized Free Cash Flow powered by strong production and high gold price environment Strong per share metrics High gold prices provide significant upside to cash generation potential No gold hedges, prepays or royalty financings 1. Pre-2024 Free Cash Flow and Operating Cash Flow per share are non-IFRS measures and have been calculated in accordance with 2024 accounting practices. See “Cautionary Statements” in this presentation for more information. 2. Represents H1 2026 figures for the 6-month period ended June 30, 2026, annualized, as reported August 5, 2026. 16 2 2 2 2
Slide 17 — Delivering Strong Returns on Capital
Delivering Strong Returns on Capital Return on Capital Employed3 Free Cash Flow Yield2 Generated $543M of Free Cash Flow1 in 2025 1. Free Cash Flow is a non-IFRS measure. See “Cautionary Statements” in this presentation. 2. Calculated as trailing 12 month Free Cash Flow over the average trailing 12 month market capitalization in USD. Free Cash Flow is a non-IFRS financial measure. See “Cautionary Statements” in this presentation. 3. Source: Capital IQ. Last 12 months after-tax EBIT over total assets less current liabilities. 17 4% 3% 14% 15% 12% 2022 2023 2024 2025 LTM Q2 26 6% 7% 9% 18% 29% 2022 2023 2024 2025 LTM Q2 26
Slide 18 — Balanced Capital Allocation
Buybacks & Dividends $203M Cash Increase $285M Exploration $40M Balanced Capital Allocation H1 2026 Growth $94M Sustaining1 $336M 1. Includes sustaining capital as well as deferred stripping and capitalized mining. Sustaining1 $165M Buybacks & Dividends $174M Cash Increase $178M Growth $118M Exploration $25M 2025 Actual 2026 Dividends 3x 2026 Buybacks up to $350M +112% Shareholder Returns
Slide 19 — A Premium Rating with the Investment Community
A Premium Rating with the Investment Community 5 Independent Chair and strong technical Directors NYSE listed in April 2026 Strong Management team 2026E FCF Yield 1 P/NAV 2 2026E EV EBITDA 3 1. Source: Capital IQ. USD as of September 10, 2026. Free Cash Flow is a non-IFRS measure. See “Cautionary Statements” in this presentation. 2. Source: Capital IQ. USD as of September 10, 2026. 3. Source: Capital IQ. Calculated current consensus Enterprise Value over Forward Consensus EBITDA in USD as of September 10, 2026. EBITDA is a non-IFRS measure. See “Cautionary Statements” in this presentation. 19 0.6x 0.7x 0.8x 0.8x 0.9x 0.9x 1.0x 1.0x 1.0x 1.0x 1.0x 1.0x 1.1x 1.2x 1.5x 1.5x BTO TXG CG AGI SSRM ELD OGC K EDV RRL IMG DPM NST EVN CDE LUG 3.3x 3.5x 3.6x 3.8x 4.4x 4.7x 5.0x 5.4x 6.5x 8.0x 8.2x 8.4x 8.6x 8.9x 9.5x 9.5x BTO OGC TXG RRL SSRM EDV IMG K CG ELD CDE NST AGI DPM LUG EVN -2.6% 1.8% 2.9% 3.5% 4.5% 6.2% 6.5% 6.9% 8.1% 9.1% 9.2% 11.2% 12.0% 13.4% 13.4% 15.2% ELD CG AGI NST EVN LUG BTO DPM SSRM CDE K RRL OGC EDV IMG TXG ELD
Slide 20 — Thesis
Global gold and copper producer with deep expertise in operations, development and exploration Committed to safe and responsible mining managing our impacts and contributing to our host communities and society Attractive financial outlook with significant production growth and Free Cash Flow1 Disciplined capital allocation focused on growth with attractive returns, a strong balance sheet and increasing returns to shareholders Focused on growing Reserves and Resources through increased investment in exploration Attractive organic growth opportunities across a diversified portfolio Investment Thesis 1. Free Cash Flow is a non-IFRS measure. See “Cautionary Statements” in this presentation. 20
Slide 21 — HAILE
HAILE Growth in the USA HAILE OVERVIEW Processing Type Carbon-in-leach flotation plant Mine Life1 2036+ Location South Carolina, USA Metals Gold, Silver Mine Type Open Pit & Underground 2026 Guidance 235 - 260 koz GOLD PRODUCTION $1,500 - $1,700/oz AISC3 ~45% of OGC’s Annual Production in 2026 2 1. Based on the technical report for Haile titled “NI 43-101 Technical Report – Haile Gold Mine Lancaster County, South Carolina”, dated March 27, 2026, with an effective date of December 31, 2025. 2. Based on the mid-point of 2026 production guidance. See Q4 2025 MD&A for further details. 3. AISC is a non-IFRS measure. See “Cautionary Statements” in this presentation. 21
Slide 22 — Exploration
Exploration $10M 2026 Exploration Guidance HAILE Continue exploration with focus on underground Leverage growing knowledge of deposit- scale controls on mineralization Advance Pisces and Clydesdale targets1 Exploring in wider district with partners Only gold producer in under-explored gold district Multi-million ounce mine with further upside potential Strategic Position Opportunity Mines & Prospects Resource Areas OGC Tenements Target Areas 1. See news release titled “OceanaGold Announces Ongoing Exploration Success at Haile” dated May 12, 2026, for more information. 22 Fourth largest operating gold mine in the United States
Slide 23 — MACRAES
MACRAES The foundation asset MACRAES OVERVIEW Processing Type Carbon-in-leach, Pressure oxidation Location South Island, New Zealand Metals Gold Mine Type Open Pit & Underground 2026 Guidance 135 - 155 koz GOLD PRODUCTION $1,950 - $2,150/oz AISC3 ~26% of OGC’s Annual Production in 20262 Mine Life1 2032+ 1. Based on the technical report for Macraes titled “NI 43-101 Technical Report – Macraes Operation Otago, New Zealand”, dated March 27, 2026, with an effective date of December 31, 2025. 2. Based on the mid-point of 2026 production guidance. See Q4 2025 MD&A for further details on guidance. 3. AISC is a non-IFRS measure. See “Cautionary Statements” in this presentation. 23
Slide 24 — Exploration
Exploration Significant ounce potential with leverage to higher gold prices Large >14,000 ha prospective land holding 30 km highly mineralized structure 6 Moz produced from 11 deposits Strategic Position Opportunity $10M 2026 Exploration Guidance MACRAES Mines & Prospects Resource Areas OGC Tenements Macraes Shear Zone 24 Mine life extension opportunities being evaluated to potentially extend mine life into the 2040s MP4 application submitted to extend mine life into the late 2030s
Slide 25 — Mine Life Extension Potential at Macraes
Mine Life Extension Potential at Macraes 1 Current reserve life to 2032 including open pit cutbacks at Coronation, Coronation North, Innes Mills and Golden Bar, and mining at Golden Point UG MP4 extends mine life to late 2030s including potential additional open pit cutbacks, development of Southern Pit Innes Mills (“SPIM”) and extensions of Golden Point Underground Opportunities to extend into the 2040s including potential mining of Round Hill, Nunns, and further exploration success ~100,000 oz/year Targeted production at Macraes to the late 2030s 1. See news release titled “OceanaGold Submits Permit Application and Provides Technical and Exploration Update Supporting Mine Life Extension at Macraes” dated September 9, 2026 for more information. MACRAES
Slide 26 — WAIHI
WAIHI The gateway to Wharekirauponga WAIHI OVERVIEW Processing Type Carbon-in-pulp Mine Life1 2038+ (MUG+WUG) Location North Island, New Zealand Metals Gold, Silver Mine Type Underground 2026 Guidance 60 - 75 koz GOLD PRODUCTION $2,100 - $2,300/oz AISC3 ~12% of OGC’s Annual Production in 20262 1. Based on the technical report titled “NI 43-101 Technical Report Waihi Operations and Wharekirauponga Underground Pre-feasibility Study, New Zealand”, dated December 11, 2024, with an effective date of June 30, 2024. 2. Based on the mid-point of 2026 production guidance. See Q4 2025 MD&A for further details on guidance. 3. AISC is a non-IFRS measure. See “Cautionary Statements” in this presentation. 26
Slide 27 — Waihi North Project Well on Track
Permits received to develop the Waihi North Project Q4 2025 Tunnelling contractor mobilized to site Q1 2026 Willows portal opening Q2 2026 Commencement of decline development Q2 2026 Services trench commissioning Q3 2026 5 drill rigs mobilized at Wharekirauponga Q3 2026 Water treatment plant staged commissioning commenced Q3 2026 Construction of vent shaft 1 commenced Q3 2026 Waihi North Project Well on Track Vent shaft 1 construction – September 2026 Water treatment plant – September 2026 27 ✓ ✓ ✓ ✓ KEY MILESTONES KEY MILESTONES – UPCOMING ✓ Early works on TSF 3 Commencement - Q4 2026 Second UG jumbo & commencing twin tunnel H1 2027 Exploration drilling from underground Mid-2027 Advancing toward the high-grade Wharekirauponga Underground ✓ ✓ ✓ WAIHI
Slide 28 — Fully permitted to develop & operate the Waihi North Project
Fully permitted to develop & operate the Waihi North Project $25M 2026 Exploration Guidance Significant Reserve growth potential at Wharekirauponga and Martha Additional discovery opportunity around epithermal alteration centres Increased drill rigs and drill sites to accelerate drilling at Wharekirauponga Large land holding centred on 3 major epithermal deposits 8 Moz high-grade epithermal district1 Strategic Position Opportunity WAIHI Epithermal Alteration OGC Tenements Known Epithermal Vein Mines & Prospects 1.2Moz of Reserves2, 800koz of Inferred2 at Wharekirauponga with strong growth potential Golden Cross Waihi (Martha UG Mine) Wharekirauponga Underground Ramarama Mataura Waiharakeke - 5865000mN - 1850000mE - 5860000mN - 1845000mE 0 2 4 km Process Plant Willows Portal WNP after-tax NPV of $621M & IRR of 24% at a gold price of $2,400/oz1 1. Based on the technical report titled “NI 43-101 Technical Report Waihi Operations and Wharekirauponga Underground Pre-feasibility Study, New Zealand”, dated December 11, 2024, effective June 30, 2024. 2. Based on Mineral Resources and Mineral Reserves estimates for the year ended December 31, 2025. See news release dated February 18, 2026 and “Appendix” in this presentation for more information. 28
Slide 29 — Further High-Grade Drill Results at Wharekirauponga
Further High-Grade Drill Results at Wharekirauponga 1 1. See news release titled “OceanaGold Reports Exceptional High-Grade Drill Results at Wharekirauponga” dated September 24, 2026, for more information. Based on Mineral Resources and Mineral Reserves estimates for the year ended December 31, 2025. Mineral Resources are inclusive of Mineral Reserves. See news release dated September 24, 2026 and “Appendix” in this presentation for more information. 1 Including 6.3 m @ 97.2 g/t Au and 8.5 m @ 41.5 g/t Au WAIHI
Slide 30 — Didipio
Didipio A strong Free Cash Flow generator with upside DIDIPIO OVERVIEW Processing Type Gravity, Flotation Mine Life1 2037 Location Luzon Island, Philippines Metals Gold & Copper Mine Type Stockpile & Underground Ownership 80% OceanaGold, 20% PSE Listed 2026 Guidance 85 – 105 koz GOLD PRODUCTION 13 – 15 kt COPPER PRODUCTION $975 - $1,100/oz AISC3 ~17% of OGC’s Annual Production in 20262 1. Based on the technical report for Didipio titled “NI 43-101 Technical Report – Didipio Mine, Luzon Island, Philippines”, dated March 27, 2026, with an effective date of December 31, 2025. 2. Based on the mid-point of 2026 production guidance. See Q4 2025 MD&A for further details on guidance. 3. AISC is a non-IFRS measure. See “Cautionary Statements” in this presentation. 30
Slide 31 — Exploration
Exploration $10M 2026 Exploration Guidance HAILE Continued growth through Resource conversion at depth Regional discovery potential across the FTAA Leverage knowledge and local team to explore porphyry analogues elsewhere in the Philippines Multi-million-ounce deposit with large and prospective land holding High-margin Copper-Gold porphry Strategic Position Opportunity DIDIPIO Intrusive Rock OGC Tenements Mines Prospects 31
Slide 32 — Katanning
Katanning High-quality development asset in Australia OVERVIEW Processing Type CIL processing Mine Life 10 years1 Location Western Australia Metals Gold Mine Type Open Pit 32 Tier-1 Jurisdiction Established infrastructure and workforce 54,000m drill program Multi-rig program currently underway Production of +100,000 oz of gold per year(1) Low capital Conventional OP with CIL processing +3,000km2 landholding in an underexplored gold belt Permitting advanced with granted mining leases KATANNING 1. See news release titled “OceanaGold Announces Acquisition of Ausgold” dated August 17, 2026 for more information.
Slide 33 — Ausgold Acquisition Delivers Growth at an Attractive Valuation
Ausgold Acquisition Delivers Growth at an Attractive Valuation Adds a high-quality development asset in a tier-1 jurisdiction 33 Conventional, low-capital project with +100koz gold production potential1 Near-term open pit development project with first gold expected in 20291 Accretive acquisition with attractive returns Accretive key per share metrics once in commercial production District-scale landholding with significant exploration upside Large +3,000km2 landholding across underexplored Katanning Greenstone Belt Leverages OceanaGold’s development and operating expertise Existing technical team in Australia with significant operating experience in the region Strong balance sheet and free cash flow generation provides ability to fund growth Ability to advance all existing organic growth projects and capital returns to shareholders 1. See news release titled “OceanaGold Announces Acquisition of Ausgold” dated August 17, 2026 for more information.
Slide 34 — Appendix
Appendix
Slide 35 — Capital Structure
Top Shareholders2 TSX / NYSE OGC Issued and Outstanding Shares1: 222M Fully Diluted Shares1: 225M Current Share Price (CAD)2: $41.87 52-Week Low / High (CAD)2: $26.54 / $59.20 Market Capitalization (CAD/USD)2: ~$9.3B/$6.7B Capitalization1 • TSX Composite • TSX Global Gold • TSX Global Mining • FTSE Mines Index Series • VanEck Junior Gold Miners (GDXJ) • VanEck Gold Miners (GDX) Analyst Coverage Capital Structure Indices Inclusion2 BMO Capital Markets Brian Quast Canaccord Genuity Jeremy Hoy CIBC World Markets Cosmos Chiu ATB Cormark Securities Richard Gray Desjardins Securities Bryce Adams Jefferies Securities, Inc. Fahad Tariq National Bank Don DeMarco Raymond James Judith Elliott RBC Capital Markets Harrison Reynolds Scotiabank Ovais Habib TD Securities Wayne Lam Cash3: $655M Debt3: - Net Cash4: $655M Leverage Ratio 0.0x Balance Sheet3 1. As at August 5, 2026. See Q2 2026 MD&A for more information. 2. Sourced from Capital IQ as at September 11, 2026. 3. As at June 30, 2026. See Q2 2026 MD&A for more information. 4. Net Cash is a non-IFRS measure. See “Cautionary Statements” in this presentation. 35
Slide 36 — Board
Board of Directors PAUL BENSON Chair GERARD BOND Executive Director LINDA BROUGHTON Non-Executive Director SANDRA DODDS Non-Executive Director STEFANIE LOADER Non-Executive Director CRAIG NELSEN Non-Executive Director ALAN PANGBOURNE Non-Executive Director IAN REID Non-Executive Director 36
Slide 37 — Diesel Price Sensitivity and Supply
Diesel consumption comprises ~6% of consolidated 2026 AISC1 guidance Majority of diesel consumption is at Haile and Macraes 80% of diesel is hedged at ~$65/bbl at Haile and Macraes, on a rolling 12-month basis Hedging program expanded to include 80% of diesel at Waihi and Didipio starting Q1 2027 Diesel Price Sensitivity and Supply No disruptions to operations to date due to Iran conflict 6% Consolidated AISC1 Diesel Oil prices to $100/bbl are expected to have ~$25/oz impact on AISC1, with hedges in place Electricity Other Materials & Consumables Labour & Related Costs 1. AISC is a non-IFRS financial measure. See “Cautionary Statements” in this presentation. Consolidated AISC represented here assumes 80% hedging. 37
Slide 38 — Proven and Probable Reserves
Proven and Probable Reserves As at December 31, 2025 Notes: • Mineral Reserves are defined by mine designs based upon the following assumptions: metal prices of US$2,200/oz gold, US$4.00/lb copper and US$25/oz silver; and NZD/USD exchange rate of 0.60. • Reported estimates of contained metal are not depleted for processing losses. • For underground Mineral Reserves, cut-offs applied to diluted grades. • Mineral Reserves are reported on a 100% basis. OceanaGold holds an 80% attributable interest in the Didipio Mine. • Haile – Open Pit: the primary cut-off grade is 0.5 g/t Au, while oxide material is assigned a cut-off grade of 0.6 g/t Au. Underground: the cut-off grade is 1.86 g/t Au. • Didipio – Gold equivalence (AuEq) is based upon the presented gold and copper prices as well as processing recoveries. AuEq = Au g/t + 1.27 x Cu%. The 13.2 Mt surface stockpile inventory includes 5.3 Mt of low-grade stocks mined at an approximate cut-off grade of 0.27 g/t AuEq. Underground: cut-off grade of 1.16 g/t AuEq is used. Incremental stopes proximal to development already planned to access main stoping areas are reported to a lower cut-off grade of 0.76 g/t AuEq. • Macraes – Open Pit: Primary cut-off grade is 0.25 g/t while Golden Bar is 0.30 g/t. Underground: Golden Point cut-off grade is 1.08 g/t Au. Stopes for which access already exists are reported to a lower cut-off grade of 0.94 g/t. • Waihi – Martha Underground cut-off grade for previously unmined stoping areas is 2.60 g/t Au, increasing to 3.2 g/t Au for stoping areas in close proximity to remnant workings. Wharekirauponga Underground cut-off grade for stopes is 2.40 g/t Au. Proven Probable Proven & Probable Tonnes (Mt) Au (g/t) Contained Ozs (Moz) Tonnes (Mt) Au (g/t) Contained Ozs (Moz) Tonnes (Mt) Au (g/t) Contained Ozs (Moz) Cut-off grade Gold Horseshoe Underground 1.52 4.39 0.21 2.63 4.24 0.36 4.14 4.29 0.57 1.86 g/t Au Palomino Underground - - - 3.62 2.96 0.34 3.62 2.96 0.34 1.86 g/t Au Ledbetter Underground - - - 4.00 3.39 0.44 4.00 3.39 0.44 1.86 g/t Au Open Pits 2.47 1.23 0.10 16.1 1.62 0.84 18.6 1.57 0.94 0.50 g/t & 0.60 g/t Au Haile Total 3.99 2.43 0.31 26.3 2.33 1.98 30.3 2.35 2.29 Didipio Underground 13.5 1.39 0.60 14.7 0.85 0.40 28.3 1.11 1.01 0.76 g/t & 1.16 g/t AuEq Didipio Open Pit Stockpile 13.2 0.30 0.13 - - - 13.2 0.30 0.13 0.27 g/t AuEq Didipio Total 26.7 0.85 0.73 14.7 0.85 0.40 41.5 0.85 1.13 Macraes Underground 0.04 2.01 0.00 2.57 1.90 0.16 2.62 1.90 0.16 1.08 g/t & 0.94 g/t Au Macraes Open Pit 11.5 0.55 0.20 19.7 0.64 0.40 31.2 0.61 0.61 0.25 g/t & 0.30 g/t Au Macraes Total 11.5 0.56 0.21 22.3 0.78 0.56 33.8 0.71 0.77 Martha Underground - - - 3.43 3.85 0.42 3.43 3.85 0.42 2.6 g/t & 3.2 g/t Au Wharekirauponga - - - 4.10 9.20 1.21 4.10 9.20 1.21 2.40 g/t Au Waihi Total - - - 7.53 6.76 1.64 7.53 6.76 1.64 Total Gold 42.3 0.92 1.25 70.9 2.01 4.58 113 1.60 5.83 Silver Horseshoe Underground 1.52 1.5 0.1 2.63 1.8 0.2 4.14 1.7 0.2 Palomino Underground - - - 3.62 2.7 0.3 3.62 2.7 0.3 Ledbetter Underground - - - 4.00 11 1.3 4.00 11 1.3 Open Pits 2.47 2.1 0.2 16.1 2.3 1.2 18.6 2.2 1.3 Haile Total 3.99 1.9 0.2 26.3 3.5 3.0 30.3 3.3 3.2 Didipio Underground 13.5 1.7 0.7 14.7 1.3 0.6 28.3 1.5 1.4 Didipio Open Pit Stockpile 13.2 1.9 0.8 - - - 13.2 1.9 0.8 Didipio Total 26.7 1.8 1.6 14.7 1.3 0.6 41.5 1.7 2.2 Martha Underground - - - 3.43 17 1.9 3.43 17 1.9 Wharekirauponga - - - 4.10 16 2.1 4.10 16 2.1 Waihi Total - - - 7.53 17 4.0 7.53 17 4.0 Total Silver 30.7 1.8 1.8 48.6 4.9 7.6 79.3 3.7 9.5 Copper Didipio Underground 13.5 0.38 0.05 14.7 0.31 0.05 28.3 0.35 0.10 Didipio Open Pit Stockpile 13.2 0.28 0.04 - - - 13.2 0.28 0.04 Didipio Total 26.7 0.33 0.09 14.7 0.31 0.05 41.5 0.32 0.13 Total Copper 26.7 0.33 0.09 14.7 0.31 0.05 41.5 0.32 0.13 38
Slide 39 — Measured, Indicated & Inferred Resources
Measured, Indicated & Inferred Resources As at December 31, 2025 Mineral Resources are reported inclusive of Mineral Reserves. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. All Mineral Resources are based on the following assumptions: metal prices of US$2,450/oz gold, US$4.50/lb copper and US$28.50/oz silver; and NZD/USD exchange rate of 0.60. • Macraes Open Pit Mineral Resources are constrained by optimised shells based upon economic assumptions above. Waihi Open Pit Mineral Resources reported within a pit design limited by infrastructural considerations. Haile Open Pit Mineral Resources reported within the reserve design pit. • Underground Mineral Resources are reported within volumes guided by conceptual stope designs which are based upon economic assumptions above and exclude dilution. • Mineral Resources are reported on a 100% basis. OceanaGold holds an 80% attributable interest in the Didipio Mine. • Haile – Open Pit primary cut-off grade is 0.50 g/t Au, while oxide cut-off grade is 0.60 g/t Au. Horseshoe, Ledbetter and Palomino Underground Mineral Resources at 1.70 g/t Au cut-off. • Didipio – 13.2 Mt surface stockpile inventory based on mining cut-off grades at the time ranging from 0.27 g/t to 0.40 AuEq. Underground Mineral Resources reported at a cut-off grade of 0.67 g/t AuEq between the 2,460mRL and 1,800mRL with AuEq cut-off grade based on presented gold and copper prices. AuEq = Au g/t + 1.27 x Cu %. • Macraes – Open Pits cut-off grades between 0.25 g/t Au and 0.40 g/t Au. Golden Point Underground cut-off grade is 0.97 g/t Au. • Waihi – Martha Underground cut-off grade is 2.15 g/t Au, Wharekirauponga cut-off grade is 1.70 g/t Au. Martha Open Pit cut-off grade is 0.5 g/t Au and Gladstone Open Pit cut-off grade is 0.56 g/t Au. Measured Indicated Measured & Indicated Inferred Tonnes (Mt) Au (g/t) Contained Ozs (Moz) Tonnes (Mt) Au (g/t) Contained Ozs (Moz) Tonnes (Mt) Au (g/t) Contained Ozs (Moz) Tonnes (Mt) Au (g/t) Contained Ozs (Moz) Cut-off grade Gold Horseshoe Underground 1.98 5.11 0.33 2.76 5.11 0.45 4.74 5.11 0.78 0.5 2.7 0.0 1.70 g/t Au Palomino Underground . . . 4.19 3.38 0.45 4.19 3.38 0.45 0.8 2.5 0.1 1.70 g/t Au Ledbetter Underground . . . 4.07 4.12 0.54 4.07 4.12 0.54 1.2 2.9 0.1 1.70 g/t Au Open Pits 2.58 1.21 0.10 16.1 1.64 0.85 18.7 1.58 0.95 0.6 0.9 0.0 0.50 g/t & 0.60 g/t Au Haile Total 4.56 2.91 0.43 27.1 2.63 2.30 31.7 2.67 2.72 3.1 2.4 0.2 Didipio Underground 14.3 1.53 0.71 17.7 0.89 0.51 32.0 1.18 1.21 9.2 0.9 0.3 0.67 g/t AuEq Open Pit Stockpiles 13.2 0.29 0.12 . . . 13.2 0.29 0.12 0.27 g/t & 0.40 g/t AuEq Didipio Total 27.5 0.94 0.83 17.7 0.89 0.51 45.2 0.92 1.34 9.2 0.9 0.3 Macraes Underground 0.08 3.02 0.01 6.37 2.28 0.47 6.45 2.29 0.47 2.4 1.8 0.1 0.97 g/t Au Open Pits 12.6 0.62 0.25 35.7 0.67 0.76 48.3 0.65 1.01 25 0.7 0.5 0.25 g/t & 0.40 g/t Au Macraes Total 12.7 0.63 0.26 42.1 0.91 1.23 54.8 0.85 1.49 27 0.8 0.7 Martha Underground 6.33 5.24 1.07 6.33 5.24 1.07 2.2 4.6 0.3 2.15 g/t Au Wharekirauponga 2.63 17.3 1.46 2.63 17.3 1.46 2.9 8.5 0.8 1.70 g/t Au Open Pits 9.72 1.76 0.55 9.72 1.76 0.55 3.2 1.8 0.2 0.50 g/t & 0.56 g/t Au Waihi Total 18.7 5.13 3.08 18.7 5.13 3.08 8.3 4.9 1.3 Total Gold 44.8 1.05 1.51 106 2.10 7.11 150 1.78 8.63 48 1.6 2.5 Silver Horseshoe Underground 1.98 1.9 0.12 2.76 2.1 0.2 4.74 2.0 0.3 0.5 1.0 0.0 Palomino Underground . . . 4.19 2.8 0.4 4.19 2.8 0.4 0.8 2.1 0.1 Ledbetter Underground . . . 4.07 12 1.6 4.07 12 1.6 1.2 7.5 0.3 Open Pits 2.58 2.2 0.18 16 .1 2.5 1.3 18.7 2.5 1.5 0.6 2.4 0.0 Haile Total 4.56 2.0 0.30 27.1 4.0 3.5 31.7 3.7 3.8 3.1 4.0 0.4 Didipio Underground 14 .3 1.8 0.8 17.7 1.4 0.8 32.0 1.6 1.6 9.2 1.2 0.4 Open Pit Stockpiles 13 .2 1.9 0.8 . . . 13.2 1.9 0.8 Didipio Total 27.5 1.8 1.6 17.7 1.4 0.8 45.2 1.7 2.4 9.2 1.2 0.4 Martha Underground 6.33 20 4.1 6.33 20 4.1 2.2 24 1.7 Wharekirauponga 2.63 27 2.3 2.63 27 2.3 2.9 13 1.2 Open Pits 9.72 10 3.2 9.7 10 3.2 3.2 9.6 1.0 Waihi Total 18.7 16 9.6 18.7 16 9.6 8.3 15 3.9 Total Silver 32 .1 1.9 1.9 63.5 6.8 14 95.6 5.1 16 21 7.1 4.7 Copper Didipio Underground 14.3 0.43 0.06 17.7 0.33 0.06 32.0 0.37 0.12 9.2 0.3 0.02 Open Pit Stockpiles 13.2 0.28 0.04 . . . 13.2 0.28 0.04 Didipio Total 27.5 0.36 0.10 17.7 0.33 0.06 45.2 0.35 0.16 9.2 0.3 0.02 Total Copper 27.5 0.36 0.10 17.7 0.33 0.06 45.2 0.35 0.16 9.2 0.3 0.02 39
Slide 40 — Technical Disclosure
Technical Disclosure Notes to Mineral Reserves and Mineral Resources Estimates All Mineral Reserves and Mineral Resources were estimated as of December 31, 2025 and have been prepared in accordance with NI 43-101. Mineral Reserves and Mineral Resources estimates are reported on a 100% basis. OceanaGold holds an 80% attributable interest in the Didipio Mine. All tonnage, grade and contained metal content estimates have been rounded; rounding may result in apparent summation differences between tonnes, grade, and contained metal content. Mineral Resources are reported inclusive of Mineral Reserves. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. It is reasonably expected that the majority of Inferred Mineral Resources could be upgraded to Indicated Mineral Resources with continued exploration; however, there is no guarantee that all or any part of an Inferred Mineral Resource will ever be upgraded to a higher category. The Mineral Resources estimate for Haile open pit has been verified and approved by, or is based on information prepared by, or under the supervision of, J. Moore, the Company’s Head of Resource Development. The Mineral Reserves estimate for Haile open pits has been verified and approved by, or is based on information prepared by, or under the supervision of, G. Hollett, the Company’s Head of Mine Engineering. The Mineral Resources estimate for Haile underground has been verified and approved by, or is based on information prepared by, or under the supervision of, D. Corley, the Company’s Principal Resource Geologist, and the Mineral Reserves estimate for Haile underground has been verified and approved by or is based upon information prepared by, or under the supervision of, B. Drury, Superintendent – Engineering Services (underground), Haile. The Mineral Resources estimate for Didipio has been verified and approved by, or is based on information prepared by, or under the supervision of, J. Moore, while the Mineral Reserves estimate for Didipio underground has been verified and approved by or is based upon information prepared by, or under the supervision of, P. Jones, the Company’s Head of Underground Mining. The Mineral Resources estimate for Macraes open pit and underground operations has been verified and approved by, or is based on information prepared by, or under the supervision of, M. Grant, the Company’s Senior Geologist – Resource Development, Macraes. The Mineral Reserves estimate for Macraes open pits has been verified and approved by, or is based on information prepared by, or under the supervision of, K. Madambi, the Company’s Manager – Technical Services & Projects, Macraes. The Mineral Reserves estimate for Macraes underground has been verified and approved by, or is based upon information prepared by, or under the supervision of, E. Leslie, the Company’s Group Mining Engineer. The Mineral Resources estimate for Waihi’s Wharekirauponga Underground, Martha Underground, Gladstone Open Pit and Martha Open Pit has been verified and approved by, or is based on information prepared by, or under the supervision of, L. Crawford-Flett, the Company’s Manager – Exploration and Geology, Waihi. The Mineral Reserves estimate for Martha Underground has been verified and approved by, or is based on information prepared by, or under the supervision of, D. Townsend, the Company’s Manager – Mining (Underground), Waihi. The Mineral Reserves estimate for the Wharekirauponga Underground has been verified and approved by, or is based upon information prepared by, or under the supervision of, E. Leslie, the Company’s Group Mining Engineer. All such persons noted above are “qualified persons” for the purposes of NI 43-101. Messrs. Crawford-Flett, Jones, Leslie, Madambi, Moore and Townsend are Members and Chartered Professionals with the Australasian Institute of Mining and Metallurgy. Messrs. Corley and Grant are members of the Australian Institute of Geoscientists. Mr. Hollett is a Professional Engineer registered with Engineers and Geoscientists of British Columbia. Ms. Drury is a Registered Member with the Society of Mining, Metallurgy & Exploration. For further scientific and technical information supporting the disclosure in this presentation (including disclosure regarding Mineral Resources and Mineral Reserves, data verification, key assumptions, parameters, methods used to estimate the Mineral Resources and Mineral Reserves, and risks and other factors), please refer to the following NI 43-101 technical reports available under the Company’s profile on SEDAR+ at www.sedarplus.ca and on the Company’s website at www.oceanagold.com: “NI 43-101 Technical Report – Haile Gold Mine, Lancaster County, South Carolina”, dated March 27, 2026 with an effective date of December 31, 2025, prepared by D. Carr, G. Hollett, B. Drury, J. Moore and D. Corley (OceanaGold), L. Standridge and R. Cook (Call & Nicholas, Inc.), J. Newton Janney-Moore and W. Kingston (NewFields Mining Design & Technical Services, LLC) and B. Miller (SRK Consulting (U.S.), Inc.); “NI 43-101 Technical Report – Macraes Operation, Otago, New Zealand”, dated March 27, 2026, with an effective date of December 31, 2025, prepared by M. Grant, K. Madambi, E. Leslie and D. Carr (OceanaGold); “NI 43-101 Technical Report Waihi District Pre-feasibility Study, New Zealand”, dated December 11, 2024 with an effective date of June 30, 2024, prepared by D. Townsend, L. Crawford-Flett, K. Hollis, E. Leslie and T. Maton (OceanaGold); and “NI 43-101 Technical Report – Didipio Mine, Luzon Island, Philippines”, dated March 27, 2026, with an effective date of December 31, 2025, prepared by D. Carr, P. Jones, and J. Moore (OceanaGold). Cautionary Statement Regarding Mineral Resources and Mineral Reserves Unless otherwise indicated, the scientific and technical disclosure in this presentation was prepared in accordance with NI 43-101, which differs from the scientific and technical disclosure requirements of the SEC that are applicable to domestic United States reporting companies. In particular, and without limiting the generality of the foregoing, the terms “Mineral Reserve”, “Proven Mineral Reserve”, “Probable Mineral Reserve”, “Inferred Mineral Resources,”, “Indicated Mineral Resources,” “Measured Mineral Resources” and “Mineral Resources” used or referenced in this news release are Canadian mineral disclosure terms as defined in accordance with NI 43-101 and the Canadian Institute of Mining, Metallurgy and Petroleum (the “CIM”) – CIM Definition Standards on Mineral Resources and Mineral Reserves, adopted by the CIM Council, as amended (the “CIM Definition Standards”). The definitions of these terms, and other mining terms and disclosures, differ from the definitions of such terms, if any, for purposes of the SEC’s disclosure rules for domestic United States reporting companies and any Mineral Reserves and Mineral Resources reported by the Company in accordance with NI 43-101 may not qualify as such under SEC standards, including Subpart 1300 of Regulation S-K under the United States Securities Exchange Act of 1934, as amended. As a foreign private issuer that is eligible to file reports with the SEC pursuant to the multi-jurisdictional disclosure system, the Company is not required to provide disclosure on its mineral properties under applicable SEC rules and regulations and provides disclosure under NI 43-101 and the CIM Definition Standards. Accordingly, Mineral Resources and Mineral Reserves information and other scientific and technical information contained or referenced in this news release may not be comparable to similar scientific and technical information disclosed by United States public companies subject to the reporting and technical disclosure requirements of the SEC. Historical results or feasibility models presented herein are not guarantees or expectations of future performance. 40
Slide 41 — VALERIE BURNS
VALERIE BURNS Director, Investor Relations BRIAN MARTIN SVP, Business Development & Investor Relations BRENDAN SPRAGUE Manager, Investor Relations 400 Burrard Street #1020 Vancouver, British Columbia V6C 3B7 Canada +1 604 678 4123 [email protected] oceanagold.com