Commitments and Contingencies	9 Months Ended
Sep. 30, 2025
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. Commitments and Contingencies The Company has certain non-cancelable purchase obligations related to the manufacturing of drug substance. The Company has agreed to purchase from Bachem Americas, Inc. a significant portion of its requirements for the pegcetacoplan drug substance. Under a commercial supply agreement with NOF Corporation ("NOF"), the Company has agreed to purchase activated polyethylene glycol derivative, or PEG, which is a component of pegcetacoplan. In September 2024, the Company terminated the minimum purchase obligation with NOF for 2025. Under these agreements, as of September 30, 2025, the Company is obligated to pay up to $94.7 million to these vendors over the next two years. As a result of the termination of the minimum purchase obligation with NOF, the Company incurred an expense of $6.4 million, which was included in cost of sales on the consolidated statements of operations and comprehensive loss for the year ended December 31, 2024. As this amount is due in January 2026, it is included in accounts payable on the condensed consolidated balance sheet as of September 30, 2025 and included in other liabilities on the condensed consolidated balance sheet as December 31, 2024. In addition, the Company has other non-cancelable purchase agreements as of September 30, 2025, under which it is obligated to pay up to $11.5 million to vendors over the next five years. The Company is a party to a master lease agreement under which the Company leases vehicles with initial terms of 36 months from the date of delivery. If the Company were unable to take delivery of a previously ordered vehicle, the Company may incur nominal fees. Indemnifications—In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend indemnified parties for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third-party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has not incurred any cost to defend lawsuits or settle claims related to these indemnification provisions. Legal—During the normal course of business, the Company may be a party to legal claims that may not be covered by insurance. In March 2025, the United States District Court for the District Court of Massachusetts dismissed, without prejudice and without leave to amend, a putative class action complaint that was filed in August 2023 against the Company and certain current and former executive officers of the Company, which alleged, among other things, that the defendants violated Sections 10(b) and/or 20(a) of the Exchange Act and Rule 10b-5 promulgated thereunder by misrepresenting and/or omitting certain material facts related to the design of SYFOVRE’s clinical trials and the risks associated with SYFOVRE’s commercial adoption, and sought, among other relief, compensatory damages and equitable relief in favor of the alleged class against all defendants, including interest, and reasonable costs and expenses incurred by plaintiffs, including attorneys’ and expert fees. In April 2025, the plaintiffs filed an appeal to the United States Court of Appeals for the First Circuit, where the case currently awaits further decision. In December 2024, purported stockholders filed putative stockholder derivative lawsuits in the United States District Court for the District of Massachusetts on behalf of the Company against the Company’s directors for breach of fiduciary duty, unjust enrichment, waste, and alleged violation of Section 14(a) of the Exchange Act related to the design of SYFOVRE’s clinical trials and the risks associated with SYFOVRE’s commercial adoption, and sought monetary and punitive damages, and costs, including attorneys’ fees. These cases were consolidated under the caption In re Apellis Pharmaceuticals, Inc. Derivative Litigation, No. 1:24-cv-13128-JEK in January 2025 and are stayed pending the outcome of the appeal in the United States Court of Appeals for the First Circuit of the dismissal of the securities class action. The Company’s businesses may also be subject at any time to commercial disputes, product liability claims, personal injury claims, third-party subpoenas or various other lawsuits arising in the ordinary course of business, including intellectual property infringement, employment or investor matters, and the Company expects that this will continue to be the case in the future.

Commitments and Contingencies

9 Months Ended

Sep. 30, 2025

Commitments and Contingencies Disclosure [Abstract]

11. Commitments and Contingencies

The Company has certain non-cancelable purchase obligations related to the manufacturing of drug substance. The Company has agreed to purchase from Bachem Americas, Inc. a significant portion of its requirements for the pegcetacoplan drug substance. Under a commercial supply agreement with NOF Corporation ("NOF"), the Company has agreed to purchase activated polyethylene glycol derivative, or PEG, which is a component of pegcetacoplan. In September 2024, the Company terminated the minimum purchase

obligation with NOF for 2025. Under these agreements, as of September 30, 2025, the Company is obligated to pay up to $94.7 million to these vendors over the next two years. As a result of the termination of the minimum purchase obligation with NOF, the Company incurred an expense of $6.4 million, which was included in cost of sales on the consolidated statements of operations and comprehensive loss for the year ended December 31, 2024. As this amount is due in January 2026, it is included in accounts payable on the condensed consolidated balance sheet as of September 30, 2025 and included in other liabilities on the condensed consolidated balance sheet as December 31, 2024.

In addition, the Company has other non-cancelable purchase agreements as of September 30, 2025, under which it is obligated to pay up to $11.5 million to vendors over the next five years.

The Company is a party to a master lease agreement under which the Company leases vehicles with initial terms of 36 months from the date of delivery. If the Company were unable to take delivery of a previously ordered vehicle, the Company may incur nominal fees.

Indemnifications—In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend indemnified parties for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third-party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has not incurred any cost to defend lawsuits or settle claims related to these indemnification provisions.

Legal—During the normal course of business, the Company may be a party to legal claims that may not be covered by insurance.

In March 2025, the United States District Court for the District Court of Massachusetts dismissed, without prejudice and without leave to amend, a putative class action complaint that was filed in August 2023 against the Company and certain current and former executive officers of the Company, which alleged, among other things, that the defendants violated Sections 10(b) and/or 20(a) of the Exchange Act and Rule 10b-5 promulgated thereunder by misrepresenting and/or omitting certain material facts related to the design of SYFOVRE’s clinical trials and the risks associated with SYFOVRE’s commercial adoption, and sought, among other relief, compensatory damages and equitable relief in favor of the alleged class against all defendants, including interest, and reasonable costs and expenses incurred by plaintiffs, including attorneys’ and expert fees. In April 2025, the plaintiffs filed an appeal to the United States Court of Appeals for the First Circuit, where the case currently awaits further decision.

In December 2024, purported stockholders filed putative stockholder derivative lawsuits in the United States District Court for the District of Massachusetts on behalf of the Company against the Company’s directors for breach of fiduciary duty, unjust enrichment, waste, and alleged violation of Section 14(a) of the Exchange Act related to the design of SYFOVRE’s clinical trials and the risks associated with SYFOVRE’s commercial adoption, and sought monetary and punitive damages, and costs, including attorneys’ fees. These cases were consolidated under the caption In re Apellis Pharmaceuticals, Inc. Derivative Litigation, No. 1:24-cv-13128-JEK in January 2025 and are stayed pending the outcome of the appeal in the United States Court of Appeals for the First Circuit of the dismissal of the securities class action.

The Company’s businesses may also be subject at any time to commercial disputes, product liability claims, personal injury claims, third-party subpoenas or various other lawsuits arising in the ordinary course of business, including intellectual property infringement, employment or investor matters, and the Company expects that this will continue to be the case in the future.