IAMGOLD CORP

Mineral Reserves decreased 640,000 ounces, primarily due to depletion (428,000 contained ounces milled) and geology model adjustments as mining activities continue to progress through the mine plan.

Essakane M&I Mineral Resources, inclusive of Mineral Reserves on a 100% basis (excluding Gossey), increased 11% to an estimated 4.4 million ounces (3.8 million ounces attributable) as of December 31, 2025, with a 50% increase in tonnes (to 150 Mt) offsetting a 26% decrease in grades (to 0.91 g/t Au, including stockpiles). The increase in tonnes and ounces underscores confidence in the potential for Essakane to extend its mine life within the fence beyond current guidance (last year Essakane processed 12.6 Mt of ore at an average head grade of 1.18 g/t Au). Inferred Mineral Resources (excluding Gossey) increased 20% from the year prior to an estimated 853,000 ounces at 1.10 g/t Au. (See "Mineral Resources and Reserves")

Nelligan Mining Complex, Quebec, Canada

On December 19, 2025, and December 22, 2025, the Company acquired all of the issued and outstanding shares of each of Northern Superior and Orbec, respectively, by way of court-approved plan of arrangement for consideration of approximately $329.0 million and $14.2 million, respectively, in shares of the Company and cash. The combined assets, together the "Nelligan Mining Complex", consolidates the Chibougamau region with a dominant land position of approximately 134,000 hectares. The Northern Superior acquisition with the Philibert, Chevrier, Lac Surprise and Croteau 1 projects together with the Orbec acquisition with the Muus project are combined with IAMGOLD's Nelligan and Monster Lake Projects. The newly combined assets, together, rank as one of the largest pre-production gold camps in Canada. The close proximity of the primary deposits to each other supports the conceptual vision of a central processing facility being fed from multiple ore sources within a 17-kilometre radius.

On February 17, 2026, the Company announced its updated Mineral Resources for the Nelligan Mining Complex. On a consolidated basis, the Nelligan Mining Complex reported a significant increase in Indicated and Inferred Mineral Resources. Indicated Resources increased 1.1 million ounces to a total of 4.3 million ounces at an average grade of 0.99 g/t Au. Inferred ounces increased 1.9 million ounces to a total of 7.5 million ounces at an average grade of 1.08 g/t Au. The Nelligan deposit reported an increase of 575,000 ounces in Indicated Mineral Resources, to a total of 3.7 million ounces at an average grade of 0.95 g/t. The increase was primarily a result of the infill program conducted last year to increase the confidence in ounces from Inferred Mineral Resources. At the time of the Northern Superior acquisition, disclosed estimates were 3.75 Moz Au Measured and Indicated Mineral Resources and 8.65 Moz Au Inferred Mineral Resources, which included Croteau. The Company opted to exclude the mineral resources previously associated with the Croteau property in its year-end update, resulting in the reported totals above. (See "Mineral Resources and Reserves")

IAMGOLD has budgeted approximately $24 million for exploration activities within the Nelligan Mining Complex for 2026. The goal of the program will be to conduct thorough testing of Philibert, expand Nelligan and continue to test Monster Lake at depth, all in support of a conceptual preliminary economic assessment in 2027. The Company is planning to test high priority targets within the region.

Subsequent to the year-end, the Company exercised the option to acquire the remaining 25% interest in the Philibert property held by SOQUEM for the payment totaling C$3.5 million, completing the consolidation of 100% of the Philibert property.

Nelligan

The Company holds a 100% interest in Nelligan located approximately 45 kilometres south of the Chapais Chibougamau area in Québec.

The diamond drilling program of 13,000 metres of expansion and delineation drilling planned for 2025 was increased by more than 3,000 metres and ended at the end of the third quarter. No additional drilling was completed in the fourth quarter 2025 and approximately 16,700 metres were drilled for the year.

On September 15, 2025, the Company provided an update on the 2025 drilling program with assay results confirming the extension of the mineralized zones of Nelligan deposit. Highlights included: 20.6 m at 1.93 g/t Au and 13.5 m at 2.17 g/t Au in hole NE-25-239, and 36.5 m at 3.03 g/t Au in hole NE-25-265 in Zone 36; 24.5 m at 3.24 g/t Au in drill hole NE-25-244, and 28.8 m at 1.00 g/t Au in drill hole NE-25-248 in the Renard Zone; and 21.0 m at 2.23 g/t Au in drill hole NE-25-244, and 7.5 m at 7.48 g/t Au and 34.5 m at 1.22 g/t Au in drill hole NE-25-256A (see news release dated September 15, 2025). The Megane Zone mineralization extends at depth but will require further drilling to delineate potential mineralized lenses to add to the current resources.

Monster Lake

The Company holds a 100% interest in the Monster Lake Gold Project, which is located approximately 15 kilometres north of Nelligan in the Chapais Chibougamau area in Québec.

The 2025 diamond drilling program was initially planned for 17,000 metres and was slightly increased to approximately 17,600 metres, all of which were completed in the third quarter 2025. It tested exploration targets along the main Monster Lake Shear Zone structural corridor and known gold mineralized lateral and depth extensions.

1. At the time of the Northern Superior acquisition, disclosed estimates were 3.75 Moz Au Measured and Indicated Mineral Resources and 8.65 Moz Au Inferred Mineral Resources, which included Croteau. As at December 31, 2025, the Company opted to exclude the mineral resources previously associated with the Croteau property in its year end update, resulting in reported totals of 4.34 Moz Au Measured and Indicated Mineral Resources and 7.50 Moz Au Inferred Mineral Resources.