OceanaGold posts excellent high-grade drill results at Wharekirauponga Project, New Zealand

OceanaGold Corp. [TSX: OGC; NYSE: OGC] reported results from 16 new drill holes from the ongoing exploration and resource conversion program at Wharekirauponga, located approximately 10 km north of the company’s Waihi Operation in New Zealand.

The company is also providing an update on the Waihi North Project, which continues to progress to plan, and on the evaluation of several value-enhancing technical studies which are expected to be included in the upcoming Waihi District technical report planned for release in January 2027. These include a potential processing plant expansion to 1.2 million tonnes per annum (Mtpa) that would support the continuation of mining at the Martha Underground mine (MUG) concurrent with mining the Wharekirauponga Underground mine (WUG) once it is in production in 2032.

Wharekirauponga Drilling Highlights (estimated true width): 6.3 metres at 97.2 g/t Au from 481.5 m, East Graben (EG) Vein (WKP146C); 8.5 m at 41.5 g/t Au from 399.0 m, EG Vein (WKP150); 9.6 m at 18.5 g/t Au from 401.0 m, EG Hanging Wall (HW) Veins (WKP146A); 6.6 m at 24.0 g/t Au from 403.4 m, including 1.2 m at 107.7 g/t Au, EG HW Veins (WKP146C); 5.9 m at 25.9 g/t Au from 485.6 m, EG Vein (WKP146B) and 4.2 m at 32.4 g/t Au from 602.9 m, EG Vein (WKP147A).

Gerard Bond, President and CEO of OceanaGold, said “Drill results from Wharekirauponga continue to demonstrate the exceptional grade and continuity of the EG Vein zone, and include some of the highest-grade intercepts reported to date. These results confirm further continuity and up-dip extension of the southern high-grade zone which currently lies outside of reported reserves, therefore representing outstanding conversion and growth potential. With five drill rigs now active and the Wharekirauponga orebody remaining open in multiple directions, we continue to accelerate drilling towards the southern end to further unlock value for shareholders at this phenomenal deposit.

“I am also excited about the upcoming Waihi District technical report. With the improved performance of the Martha Underground and good drilling results, we see the potential to extend the life of the Martha Underground and increase processing capacity from that assumed in our last technical report which would enable concurrent mining and processing of both Martha and Wharekirauponga ore, driving increased value for the Waihi District.”

Drill results reflect only those set forth in OceanaGold’s news release dated September 24, 2026, and do not include all historical results except those relevant to the current Wharekirauponga drill program.

Construction and underground tunnelling activities at the Waihi North Project continue to advance to plan. Decline development, which commenced in May 2026, has advanced approximately 350 metres to date. Construction of the first ventilation shaft has commenced, with a second jumbo expected to be added in the first half of 2027 to begin development of the twin tunnel toward the Wharekirauponga orebody

Bulk earthworks at the Willows Portal site continue, with water management related activities involving sedimentation ponds, haul roads, waste rock stack and magazine now completed, and the surface facilities area remaining on track for completion by year-end. The water treatment plant began staged commissioning in September 2026 and early works on the new tailings storage facility are expected to commence in the fourth quarter of this year.

The Waihi District comprises the company’s Waihi Operation, which includes the currently producing Martha Underground (MUG), and the Waihi North Project, which includes Wharekirauponga Underground (WUG).

An updated NI 43-101 technical report on the Waihi District is planned for release in January 2027 and will include updated Mineral Reserves and Mineral Resources estimates.

The technical report is planned to include an updated mine plan for the Waihi District, incorporating the results of ongoing technical evaluations. These evaluations are assessing the potential to extend mining at MUG beyond 2033, in conjunction with the commencement of mining at WUG.

To support this opportunity, the company is also evaluating a potential processing plant expansion to increase throughput capacity up to 1.2 Mtpa from the 0.8 Mtpa contemplated in the previous technical report.

Drilling at Wharekirauponga has accelerated with the recent expansion of the fleet to five active rigs, and the construction of a new drill site (Drill Site 10), which is strategically positioned to better target the open southern high-grade zone.

Since the April 1, 2026 news release, a total of 16 drill holes have been completed from five drill sites with results returned from the EG, HW and footwall (FW) Veins, collectively referred to as the EG Vein zone. Results both within the EG Vein and its HW structures continue to confirm continuity and quality of the southern high-grade zone. Importantly, this area remains unconstrained, with mineralization open along strike, up-dip and at depth, and significant scope remains to further grow the Mineral Resource through additional drilling.

Drilling on the EG Vein returned multiple wide, high-grade intercepts demonstrating the continuity of the system to the south. Results include 6.3 metres at 97.2 g/t gold (WKP146C) in the upper part of the vein, one of the highest-grade results returned to date. Nearby holes, including 5.9 metres at 25.9 g/t Au (WKP146B) and 4.2 metres at 32.4 g/t Au (WKP147A), also returned high-grade intercepts confirming the grade and continuity of the vein in this area. A further 110 metres to the north, drill hole WKP150 returned 8.5 metres at 41.5 g/t Au, strengthening confidence in the continuity, thickness and grade of the EG Vein in this area.

Across the sixteen EG Vein intercepts reported, results continue to extend mineralization up-dip, demonstrating incremental growth of the southern high-grade zone.

This drilling supports the potential upgrade of a substantial portion of the southern high-grade zone from Inferred to Indicated Mineral Resources, underpinning an expected increase to Mineral Reserves in the company’s 2026 year-end Mineral Resource and Mineral Reserve statement and in the upcoming NI 43-101 technical report.

The Hanging Wall (HW) Veins and associated sub-parallel structures that lie immediately west of the EG Vein also yielded strong results. Drilling of the HW Veins continues to demonstrate a broadening zone of mineralization, headlined by 9.6 metres at 18.5 g/t Au and 1.2 metres at 107.7 g/t Au (WKP146A and WKP146C, respectively). Refer to original press release for complete assays.

Several holes, notably WKP146C, which returned three separate high-grade HW intercepts in addition to its EG Vein result, intersected multiple, closely stacked mineralized structures, pointing to a well-developed vein array in this part of the system. These results continue to highlight a zone of high-grade mineralization outside the current resource model, which remains a target for future growth.

With five active drill rigs now operating at Wharekirauponga, drilling through the remainder of 2026 will focus on both resource conversion and growth-oriented step-out drilling along strike of the EG Vein, reflecting the substantial upside that remains in this open, unconstrained vein system.

OceanaGold is a global intermediate gold and copper producer committed to safely and responsibly maximizing the generation of Free Cash Flow from our operations and delivering strong returns for our shareholders. We have a portfolio of four operating mines: the wholly-owned Haile Gold Mine in the United States of America; the wholly-owned Macraes and Waihi Operations in New Zealand; and the 80%-owned Didipio Mine in the Philippines.