Other Events. On September 3, 2026, Ionis announced that the U.S. FDA has approved ZANVASTRO™ (zilganersen) for the treatment of AxD in pediatric and adult patients. ZANVASTRO is the first and only disease modifying treatment for AxD, an ultra-rare, progressive and often fatal neurological disorder that can affect motor, cognitive, autonomic and gastrointestinal function. Until now, treatment of AxD has primarily been limited to managing symptoms. ZANVASTRO is an RNA-targeted medicine designe…

Results of Operations and Financial Condition. On July 29, 2026, Ionis Pharmaceuticals, Inc. (the “ Company ”) issued a press release announcing the Company’s financial results for the quarter ended June 30, 2026. In addition to disclosing results that are determined in accordance with Generally Accepted Accounting Principles (“ GAAP ”), the Company also discloses pro forma or non-GAAP results of operations, which are adjusted from GAAP to exclude non-cash compensation expense related to equi…

Other Events. On June 24, 2026, Ionis announced that the U.S. FDA has approved TRYNGOLZA® (olezarsen) as an adjunct to diet to reduce triglycerides and the risk of acute pancreatitis in adults with sHTG. TRYNGOLZA is available in a 50 mg or 80 mg dose and is self-administered once monthly via an autoinjector. sHTG is characterized by an increased risk of acute pancreatitis, which causes debilitating abdominal pain that often leads to repeated and prolonged hospitalization, permanent organ dam…

Director — Ludwig N. Hantson: Dr. Ludwig N. Hantson was appointed as a member of the Board of Directors.

Other Events. On May 28, 2026, Ionis announced that its partner, GSK, reported positive pivotal data for bepirovirsen, an investigational ASO for the treatment of CHB. Results from the two Phase 3 trials, B-Well 1 and B-Well 2, were simultaneously published in the New England Journal of Medicine and presented at the European Association for the Study of the Liver (“ EASL ”) congress. GSK licensed bepirovirsen from Ionis and the two companies have collaborated on its development. Pooled data f…

Results of Operations and Financial Condition. On April 29, 2026, Ionis Pharmaceuticals, Inc. (the “ Company ”) issued a press release announcing the Company’s financial results for the quarter ended March 31, 2026. In addition to disclosing results that are determined in accordance with Generally Accepted Accounting Principles (“ GAAP ”), the Company also discloses pro forma or non-GAAP results of operations, which are adjusted from GAAP to exclude non-cash compensation expense related to eq…

Director — B. Lynne Parshall and Joseph H. Wender: Two long-serving directors are retiring from the Board, but a new director is being appointed.

Results of Operations and Financial Condition. On February 25, 2026, Ionis Pharmaceuticals, Inc. (the “ Company ”) issued a press release announcing the Company’s financial results for the quarter and fiscal year ended December 31, 2025. In addition to disclosing results that are determined in accordance with Generally Accepted Accounting Principles (“ GAAP ”), the Company also discloses pro forma or non-GAAP results of operations, which are adjusted from GAAP to exclude non-cash compensation…

Results of Operations and Financial Condition. On January 12, 2026, Ionis Pharmaceuticals, Inc. (the “ Company ”) issued a press release announcing TRYNGOLZA ® 2025 preliminary U.S. net product sales of $105 million. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. The preliminary selected financial results reported by the Company are unaudited, subject to adjustment, and provided as an approximation in advance of the Company’s announcement of compl…

Other Events. On January 7, 2026, we announced that our partner, GSK, reported positive results from two pivotal Phase 3 studies, B-Well 1 and B-Well 2, evaluating the safety and efficacy of bepirovirsen, an investigational ASO for the treatment of CHB. The studies included over 1,800 patients from 29 countries. GSK licensed bepirovirsen from us and we have collaborated on its development. CHB is a major health challenge affecting over 250 million people worldwide and is the leading cause of…

Entry into a Material Definitive Agreement. On November 17, 2025, Ionis Pharmaceuticals, Inc. (the “Company”) completed its previously announced private offering (the “Offering”) of $770.0 million aggregate principal amount of 0.00% Convertible Senior Notes due 2030 (the “Notes”), including the exercise in full of the initial purchasers’ option to purchase up to an additional $70.0 million principal amount of Notes. The Notes were issued pursuant to an indenture, dated November 17, 2025 (the…

Unregistered Sale of Equity Securities. The information set forth under

Other Events. On November 11, 2025, the Company issued a press release announcing the proposed Offering. A copy of the press release is attached hereto as Exhibit 99.1. On November 12, 2025, the Company issued a press release announcing the pricing of the Offering. A copy of the press release is attached hereto as Exhibit 99.2. Forward-Looking Statements This Current Report on Form 8-K contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information set forth under

Other Events. On November 8, 2025, we announced positive results from the pivotal Phase 3 CORE and CORE2 studies of olezarsen in people with sHTG. The studies met the primary endpoint, with olezarsen achieving a highly statistically significant placebo-adjusted mean reduction in fasting triglyceride (TG) levels of up to 72% at six months. The reductions were sustained through 12 months. Olezarsen showed a highly statistically significant 85% reduction in acute pancreatitis events, the first a…

Entry Into a Material Definitive Agreement On October 28, 2025, Ionis Pharmaceuticals, Inc. (the “ Company ”) and Richard Geary entered into an Advisory Services Agreement (the “ Agreement ”) pursuant to which Dr. Geary will provide advisory services to the Company following his retirement from the Company in January 2026. The term of the Agreement will begin on January 16, 2026, and will continue through February 13, 2027 (the “ Advisory Period ”), but may be terminated earlier by either par…

Results of Operations and Financial Condition. On October 29, 2025, Ionis Pharmaceuticals, Inc. (the “ Company ”) issued a press release announcing the Company’s financial results for the quarter ended September 30, 2025. In addition to disclosing results that are determined in accordance with Generally Accepted Accounting Principles (“ GAAP ”), the Company also discloses pro forma or non-GAAP results of operations, which are adjusted from GAAP to exclude non-cash compensation expense related…

Other Events. On September 22, 2025, we announced positive topline results from the pivotal study of zilganersen in children and adults living with AxD, a rare, progressive and often fatal neurological condition with no approved disease-modifying treatments. Zilganersen 50 mg demonstrated statistically significant and clinically meaningful stabilization on the primary endpoint of gait speed as assessed by the 10-Meter Walk Test compared to control at week 61 (mean difference 33.3%, p=0.0412)…

Other Events. On September 2, 2025, we announced positive topline results from the pivotal Phase 3 CORE and CORE2 studies of olezarsen in people with sHTG. In the studies, olezarsen demonstrated a highly statistically significant placebo-adjusted mean reduction in fasting triglycerides of up to 72% and a highly statistically significant reduction in acute pancreatitis events of 85% with favorable safety and tolerability. CORE and CORE2 make up the largest pivotal program for sHTG, with nearly…

Other Events. On August 21, 2025, we announced that the FDA has approved DAWNZERA™ (donidalorsen) for prophylaxis to prevent attacks of HAE in adult and pediatric patients 12 years of age and older. DAWNZERA is the first and only RNA-targeted medicine approved for HAE, designed to target plasma prekallikrein, a key protein that activates inflammatory mediators associated with acute attacks of HAE. DAWNZERA 80mg is self-administered via subcutaneous autoinjector once every four (“Q4W”) or eigh…

Results of Operations and Financial Condition. On July 30, 2025, Ionis Pharmaceuticals, Inc. (the “ Company ”) issued a press release announcing the Company’s financial results for the quarter ended June 30, 2025. In addition to disclosing results that are determined in accordance with Generally Accepted Accounting Principles (“ GAAP ”), the Company also discloses pro forma or non-GAAP results of operations, which are adjusted from GAAP to exclude non-cash compensation expense related to equi…

Executive Vice President and Chief Development Officer — Richard Geary Ph.D.: Dr. Richard Geary is retiring and will be succeeded by Holly Kordasiewicz, Ph.D.

Results of Operations and Financial Condition. On April 30, 2025, Ionis Pharmaceuticals, Inc. (the “ Company ”) issued a press release announcing the Company’s financial results for the quarter ended March 31, 2025. In addition to disclosing results that are determined in accordance with Generally Accepted Accounting Principles (“ GAAP ”), the Company also discloses pro forma or non-GAAP results of operations, which are adjusted from GAAP to exclude non-cash compensation expense related to eq…

Entry into a Material Definitive Agreement. On March 11, 2025, Ionis Pharmaceuticals, Inc. (the “ Company ”), issued a press release announcing that the Company has entered into a license agreement with Ono Pharmaceutical Co., Ltd. (“ Ono ”) under which Ono obtains exclusive global rights for the development and commercialization of sapablursen, an investigational RNA-targeted medicine for polycythemia vera. A copy of this press release is attached as Exhibit 99.1 to this Current Report and i…

Results of Operations and Financial Condition. On February 19, 2025, Ionis Pharmaceuticals, Inc. (the “ Company ”) issued a press release announcing the Company’s financial results for the quarter and fiscal year ended December 31, 2024. In addition to disclosing results that are determined in accordance with Generally Accepted Accounting Principles (“ GAAP ”), the Company also discloses pro forma or non-GAAP results of operations, which are adjusted from GAAP to exclude non-cash compensation…