Sellas Life Sciences Group, Inc.

SLS·NASDAQ·$8.12Share Price as of 11/2·$1BMarket Cap as of 11/2

Financials

10-QQ2 ended 06/30/2608/11/26 10-QQ1 ended 03/31/2605/12/26 10-KFY 202503/19/26 10-QQ3 ended 09/30/2511/12/25 10-QQ2 ended 06/30/2508/12/25

Disclosures

8-KCurrent report08/11/26 8-KCurrent report07/27/26 8-KCurrent report06/25/26 8-KCurrent report06/18/26 8-KCurrent report06/02/26

Prospectuses and Registrations

S-8Registration of securities for employees06/16/26 S-3ASRAutomatic shelf registration03/20/26 424B5Prospectus supplement10/27/25 S-3Shelf registration10/10/25 S-8Registration of securities for employees08/12/25

Proxies

DEF 14ADefinitive proxy04/23/26 DEFA14AAdditional proxy materials04/23/26 DEFA14AAdditional proxy materials06/10/25 DEF 14ADefinitive proxy04/23/25 DEFA14AAdditional proxy materials04/23/25

Ownership

SC 13GBeneficial ownership08/07/26 SC 13GBeneficial ownership07/31/26 Form 4Insider transaction06/18/26 SC 13G/ABeneficial ownership (amended)03/27/26 SC 13G/ABeneficial ownership (amended)02/17/26

Other

ARSAnnual report to shareholders04/23/26 EFFECTRequest for effectiveness11/25/25 CORRESPCorrespondence with the SEC11/21/25 ARSAnnual report to shareholders04/23/25 EFFECTRequest for effectiveness05/01/24