[424B5] Equillium, Inc. Prospectus Supplement (Debt Securities)
Equillium, Inc. reports an estimated public float of $93.7 million, calculated from 47,085,662 shares held by non-affiliates and a per‑share price of $1.99. The $1.99 price was the highest closing price on The Nasdaq Capital Market within 60 days of this prospectus supplement's filing, specifically on September 11, 2025. The public float figure follows the method in General Instruction I.B.6 of Form S-3 under the Securities Act of 1933.
The company notes this figure is specific to the current filing and that if it later becomes subject to the limitations in General Instruction I.B.6, it will file another supplement to update the ATM prospectus. No other financial results, transactions, or forward-looking statements are provided in this excerpt.
La società nota che questa cifra è specifica alla presente presentazione e che, se in seguito dovesse essere soggetta alle limitazioni della General Instruction I.B.6, presenterà un altro supplemento per aggiornare il prospetto ATM. In questo estratto non sono forniti altri risultati finanziari, transazioni o dichiarazioni prospettiche.
La empresa señala que esta cifra es específica para la presente presentación y que si más adelante se somete a las limitaciones de la General Instruction I.B.6, presentará otro suplemento para actualizar el prospecto ATM. En este extracto no se proporcionan otros resultados financieros, transacciones o declaraciones prospectivas.
회사 측은 이 수치가 현재 제출에 대해 구체적임을 밝히며, 이후 일반 지침 I.B.6의 제한을 받게 될 경우 ATM Prospectus를 업데이트하기 위한 다른 보충서를 제출하겠다고 합니다. 이 발췄에 다른 재무 결과, 거래 또는 예측 진술은 제공되지 않습니다.
La société précise que ce chiffre est spécifique à la présente mise à jour et que, si plus tard il venait à être soumis aux limitations de l'Instruction générale I.B.6, elle déposera un autre supplément pour mettre à jour le prospectus ATM. Aucune autre information financière, transaction ou déclaration prospective n'est fournie dans cet extrait.
Das Unternehmen weist darauf hin, dass diese Zahl spezifisch für die gegenwärtige Einreichung ist und dass sie, falls sie später den Beschränkungen in General Instruction I.B.6 unterliegt, ein weiteres Supplemental zur Aktualisierung des ATM-Prospektes einreichen wird. In diesem Auszug werden keine weiteren finanziellen Ergebnisse, Transaktionen oder zukunftsgerichteten Aussagen bereitgestellt.
وتشير الشركة إلى أن هذا الرقم محدد للتقديم الحالي، وإذا ما خضع لاحقاً للقيود الواردة في General Instruction I.B.6، ستقدم ملحقاً آخر لتحديث نشرة ATM. لا توجد نتائج مالية أخرى، أو معاملات، أو تصريحات مستقبلية مقدمة في هذا المقتبس.
公司指出，该数字仅适用于当前提交；如果日后受到 General Instruction I.B.6 的限制，将再提交一份补充以更新 ATM 招股说明书。在本摘录中未提供其他财务结果、交易或前瞻性陈述。
- Provides a clear public float amount of $93.7 million with the underlying share count and price disclosed
- Explains calculation methodology referencing General Instruction I.B.6 of Form S-3 and the 60‑day highest closing price rule
- Commits to update the prospectus if the company becomes subject to the limitations in General Instruction I.B.6
- None.
Insights
TL;DR: The filing gives a clear, standards-based public float calculation and signals intent to update if future limits apply.
Equillium discloses the mechanics of its public float in accordance with Form S-3 guidance, specifying the non-affiliate share count (47,085,662) and the reference highest closing price within the 60‑day lookback ($1.99 on September 11, 2025). This disclosure supports eligibility assessments for shelf registration and At-The-Market (ATM) offerings by documenting the calculation methodology and the company’s commitment to file supplements if instruction I.B.6 limitations become relevant.
TL;DR: The prospectus supplement transparently documents the public float and the company’s process for future updates.
The statement is concise and compliant: it identifies the precise share count and price used to compute public float and references the governing instruction. It also alerts investors that the company will amend the prospectus if its reporting status under General Instruction I.B.6 changes. The excerpt does not include other governance or operational details.
La società nota che questa cifra è specifica alla presente presentazione e che, se in seguito dovesse essere soggetta alle limitazioni della General Instruction I.B.6, presenterà un altro supplemento per aggiornare il prospetto ATM. In questo estratto non sono forniti altri risultati finanziari, transazioni o dichiarazioni prospettiche.
La empresa señala que esta cifra es específica para la presente presentación y que si más adelante se somete a las limitaciones de la General Instruction I.B.6, presentará otro suplemento para actualizar el prospecto ATM. En este extracto no se proporcionan otros resultados financieros, transacciones o declaraciones prospectivas.
회사 측은 이 수치가 현재 제출에 대해 구체적임을 밝히며, 이후 일반 지침 I.B.6의 제한을 받게 될 경우 ATM Prospectus를 업데이트하기 위한 다른 보충서를 제출하겠다고 합니다. 이 발췄에 다른 재무 결과, 거래 또는 예측 진술은 제공되지 않습니다.
La société précise que ce chiffre est spécifique à la présente mise à jour et que, si plus tard il venait à être soumis aux limitations de l'Instruction générale I.B.6, elle déposera un autre supplément pour mettre à jour le prospectus ATM. Aucune autre information financière, transaction ou déclaration prospective n'est fournie dans cet extrait.
Das Unternehmen weist darauf hin, dass diese Zahl spezifisch für die gegenwärtige Einreichung ist und dass sie, falls sie später den Beschränkungen in General Instruction I.B.6 unterliegt, ein weiteres Supplemental zur Aktualisierung des ATM-Prospektes einreichen wird. In diesem Auszug werden keine weiteren finanziellen Ergebnisse, Transaktionen oder zukunftsgerichteten Aussagen bereitgestellt.
Filed Pursuant to Rule 424(b)(5)
Registration No. 333-269153
PROSPECTUS SUPPLEMENT
(To Prospectus Supplements dated February 23, 2024 and October 5, 2023,
and Prospectus dated January 18, 2023)
Up to $75,000,000
Common Stock
This prospectus supplement (the “Prospectus Supplement”) amends and supplements the information in the prospectus dated January 18, 2023 (the “Prior Prospectus”), filed with the Securities and Exchange Commission (the “SEC”) as part of our registration statement on Form S-3 (File No. 333-269153) (the “Registration Statement”), as previously amended and supplemented by our prospectus supplements dated October 5, 2023 and February 23, 2024 (together with the Prior Prospectus, the “ATM Prospectus”), relating to the offer and sale of shares of our common stock, $0.0001 par value per share, having an aggregate offering price of up to $21,950,000 pursuant to the terms of that certain Open Market Sale Agreement (the “Original Sales Agreement”) dated October 5, 2023, with Jefferies LLC (“Jefferies”). On August 3, 2025, we entered into that certain Amendment No. 1 to the Original Sales Agreement (as amended, the “Sales Agreement”), pursuant to which Jefferies was replaced as the sales agent by LifeSci Capital LLC (the “Sales Agent”). As disclosed in our Current Report on Form 8-K filed with the SEC on August 4, 2025, all references to Jefferies in the ATM Prospectus shall now refer to the Sales Agent. This Prospectus Supplement should be read in conjunction with the ATM Prospectus, and is qualified by reference thereto, except to the extent that the information herein amends or supersedes the information contained in the ATM Prospectus. This Prospectus Supplement is not complete without, and may only be delivered or utilized in connection with, the ATM Prospectus, and any future amendments or supplements thereto.
As of the date hereof, the aggregate market value of our outstanding common stock held by non-affiliates (our “public float”), calculated in accordance with General Instruction I.B.6 of Form S-3 under the Securities Act of 1933, as amended, was approximately $93.7 million, which was calculated based on 47,085,662 shares of our outstanding common stock held by non-affiliates as of September 4, 2025, at a price of $1.99 per share as of September 11, 2025, which was the highest closing price of our common stock on The Nasdaq Capital Market within 60 days of the filing of this Prospectus Supplement.
We are filing this Prospectus Supplement to amend the ATM Prospectus to update our public float, and indicate that, since our public float is above $75.0 million, we are no longer subject to the sales limitations of General Instruction I.B.6 of Form S-3 with respect to the Registration Statement of which the ATM Prospectus, as amended by this Prospectus Supplement, forms a part. If we become subject to the limitations of General Instruction I.B.6 in the future, we will file another supplement to the ATM Prospectus, as amended by this Prospectus Supplement.
Since our entry into the Sales Agreement, we have sold approximately $0.96 million of common stock pursuant to the Sales Agreement. Accordingly, because we are no longer subject to the sales limitations of General Instruction I.B.6, we may offer and sell up to an additional $74.0 million of shares of our common stock pursuant to the Sales Agreement from time to time through the Sales Agent.
Our common stock trades on the Nasdaq Capital Market under the symbol “EQ.” On September 18, 2025, the last reported sale price of our common stock on the Nasdaq Capital Market was $1.50 per share.
Investing in our securities involves a high degree of risk. Before making an investment decision, please read the information under “Risk Factors” on page S-7 of the Prior Prospectus and in the documents incorporated by reference into this Prospectus Supplement and the ATM Prospectus, and under similar headings in the other documents that are filed after the date hereof and incorporated by reference into this Prospectus Supplement and the ATM Prospectus.
Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this Prospectus Supplement or the ATM Prospectus. Any representation to the contrary is a criminal offense.
LifeSci Capital
The date of this Prospectus Supplement is September 19, 2025.
FAQ
What is Equillium's (EQ) reported public float in this prospectus supplement?
How was the $93.7 million public float calculated for EQ?
Does Equillium (EQ) say it will update the public float if circumstances change?
Does this excerpt contain earnings, transaction, or forward-looking financial details?
