[424B3] Autolus Therapeutics plc American Depositary Share Prospectus Filed Pursuant to Rule 424(b)(3)

Rhea-AI Filing Summary

Autolus Therapeutics plc (NASDAQ: AUTL) filed Prospectus Supplement No. 2 dated 30 June 2025, updating its S-1 prospectus dated 15 May 2025. The supplement incorporates the company’s Form 8-K filed 27 June 2025 and chiefly concerns the potential resale of up to 54,584,250 American Depositary Shares (ADSs) by existing selling securityholders. The registration covers (i) 51,318,944 ADSs that are already outstanding and (ii) 3,265,306 ADSs issuable upon exercise of outstanding warrants. No new capital will be raised by the company through this resale registration.

The ADSs trade on the Nasdaq Global Select Market under the symbol “AUTL” and closed at $2.31 on 27 June 2025.

The supplement attaches the company’s Form 8-K detailing results of the 2025 Annual General Meeting (AGM) held on 26 June 2025. Shareholders approved all nine resolutions on a poll basis, including:

• Adoption of the FY 2024 Annual Report and Financial Statements (219.8 m for, 97.5 k against).
• Directors’ remuneration report (216.0 m for, 4.29 m against).
• Directors’ remuneration policy (203.4 m for, 16.93 m against).
• Re-appointment of Ernst & Young LLP as auditors (220.27 m for, 110.2 k against).
• Re-election of directors Dr. R. Iannone (199.0 m for, 20.75 m against) and Dr. R. Rao (219.96 m for, 194.7 k against).
• Approval of a new Employee Share Purchase Plan with a 3,000,000-share pool (219.65 m for, 706.8 k against).

The filing also reiterates standard risk disclosures and reminds investors to review the “Risk Factors” section of the original prospectus and the company’s periodic reports.

No earnings, guidance, or transactional updates are included; the document is limited to resale registration logistics and routine corporate-governance matters.

Positive

• All nine AGM resolutions passed, demonstrating broad shareholder support.
• Re-appointment of Ernst & Young LLP ensures continuity in audit oversight with only 0.05 % votes against.
• Employee Share Purchase Plan approved, enhancing workforce alignment while limiting share issuance to 3 m.

Negative

• Registration statement enables resale of 54.6 m ADSs, potentially increasing share supply once selling securityholders act.
• 16.9 m votes against the remuneration policy indicate measurable shareholder dissent on executive pay.
• 3 m shares authorized for the Employee Share Purchase Plan introduce modest future dilution.

Insights

Financial Analyst

TL;DR – Routine AGM approvals; large resale registration could add technical supply but no direct dilution or capital raise.

The prospectus supplement does not introduce new securities; it merely registers shares already issued or issuable under outstanding warrants, allowing existing holders to sell. As a result, Autolus receives no proceeds and there is no immediate balance-sheet impact. However, authorizing resale of roughly 54.6 m ADSs (well above recent average trading volume) may create overhang once holders decide to transact. AGM voting showed strong shareholder support for management—most resolutions passed with >90 % affirmative votes—although the remuneration policy drew a notable 16.9 m opposing votes, hinting at some pay-related dissent. Approval of the 3 m-share Employee Share Purchase Plan is modest relative to total outstanding shares and aligns incentives. Overall, the filing is housekeeping in nature and should be viewed as neutral unless selling pressure materializes.

Corporate Governance Expert

TL;DR – Governance items passed comfortably; minor dissent on pay; auditor reappointment continues oversight stability.

From a governance standpoint, Autolus achieved clear majorities on all nine resolutions, signaling broad investor confidence. The remuneration policy received 203.4 m votes for and 16.9 m against—an 89 % approval that is acceptable but worth monitoring. Both directors standing for re-election secured their seats, though Dr. Iannone attracted a 9.4 % opposition rate, higher than Dr. Rao’s 0.1 %. Re-appointing Ernst & Young LLP with virtually no opposition suggests continuity in audit oversight. The new Employee Share Purchase Plan, capped at 3 m shares, reinforces employee alignment with shareholder interests while introducing limited dilution potential. Overall governance risks remain low.

Filed pursuant to Rule 424(b)(3)

Registration No. 333-287097

PROSPECTUS SUPPLEMENT NO. 2

(To the prospectus dated May 15, 2025)

Up to 54,584,250 American Depositary Shares Representing 54,584,250 Ordinary Shares Offered by Selling Securityholders

This prospectus supplement supplements the prospectus, dated May 15, 2025 (the “Prospectus”), which forms a part of our registration statement on Form S-1 (No. 333-287097). This prospectus supplement is being filed to update and supplement the information in the Prospectus with the information contained in our Report on Form 8-K filed with the Securities and Exchange Commission (the “SEC”) on June 27, 2025 (the “Report”). Accordingly, we have attached the Report to this prospectus supplement.

The Prospectus and this prospectus supplement relate to the resale from time to time by the selling securityholders identified in the Prospectus, of up to 54,584,250 American Depositary Shares, or ADSs, consisting of (i) 51,318,944 ADSs, representing 51,318,944 of our ordinary shares, with a nominal value of $0.000042 per share, and (ii) up to an aggregate of 3,265,306 ADSs issuable upon the exercise of outstanding warrants to purchase our ADSs, representing 3,265,306 ordinary shares.

The ADSs are listed on the Nasdaq Global Select Market, or Nasdaq, under the symbol “AUTL.” On June 27, 2025, the closing sale price of the ADSs on Nasdaq was $2.31.

This prospectus supplement should be read in conjunction with the Prospectus, including any amendments or supplements thereto, which is to be delivered with this prospectus supplement. This prospectus supplement is qualified by reference to the Prospectus, including any amendments or supplements thereto, except to the extent that the information in this prospectus supplement updates and supersedes the information contained therein.

This prospectus supplement is not complete without, and may not be delivered or utilized except in connection with, the Prospectus, including any amendments or supplements thereto.

You should read this prospectus supplement carefully before you invest in our securities. Investing in our securities involves risks. You should consider carefully the risks that we have described under the caption “Risk Factors” on page 6 of the Prospectus and in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, our Quarterly Report on Form 10-Q for the fiscal quarter ended March 31, 2025 and our other filings with the SEC.

Neither the SEC 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 Prospectus. Any representation to the contrary is a criminal offense.

PROSPECTUS SUPPLEMENT DATED JUNE 30, 2025

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): June 26, 2025

Autolus Therapeutics plc

(Exact name of registrant as specified in its Charter)

England and Wales			001-38547						Not applicable
(State or other jurisdiction of incorporation or organization)			(Commission File Number)						(I.R.S. Employer Identification No.)
The Mediaworks
191 Wood Lane
London						W12 7FP
United Kingdom
(Address of principal executive offices)(Zip Code)
(44) 20						3829 6230
(Registrant's telephone number, including area code)
Not Applicable
(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐			Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
☐			Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
☐			Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
☐			Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class			Trading Symbol(s)			Name of each exchange on which registered
American Depositary Shares, each representing one ordinary share, nominal value $0.000042 per share			AUTL			The Nasdaq Global Select Market
Ordinary shares, nominal value $0.000042 per share*			*			The Nasdaq Stock Market LLC*

* Not for trading, but only in connection with the listing of the American Depositary Shares on The Nasdaq Global Select Market. The American Depositary Shares represent the right to receive ordinary shares and are being registered under the Securities Act of 1933, as amended, pursuant to a separate Registration Statement on Form F-6. Accordingly, the American Depositary Shares are exempt from the operation of Section 12(a) of the Securities Exchange Act of 1934, as amended, pursuant to Rule 12a-8 thereunder.

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 5.07 Submission of Matters to a Vote of Security Holders.

On June 26, 2025, Autolus Therapeutics plc (the “Company”) held its 2025 Annual General Meeting of Shareholders (the “AGM”). The shareholders considered the nine resolutions set forth below, each of which were voted on and duly passed on a poll at the AGM. Each resolution is described in more detail in the Company’s definitive proxy statement filed with the Securities and Exchange Commission on June 02, 2025 (the “Proxy Statement”). Set forth below are the results, including the number of votes cast for, against and abstentions, with respect to each of the resolutions submitted for a vote of the shareholders at the AGM. An abstention is not a vote in law and is not counted in the calculation of the proportion of the votes for or against a particular resolution.

Ordinary Resolutions

Resolution 1: To receive and adopt the Company’s accounts for the financial year ended 31 December 2024 and the associated reports of the Directors and auditors (the “2024 Annual Report and Financial Statements”). The votes were cast as follows:

For			Against			Abstain
219,809,664			97,503			477,332

Resolution 2: To approve the Directors’ remuneration report (excluding the Directors’ remuneration policy), as set out on pages 36 to 65 of the 2024 Annual Report and Accounts. The votes were cast as follows:

For			Against			Abstain
216,036,710			4,285,817			61,972

Resolution 3: To approve the Directors’ remuneration policy contained in pages 39 to 52 of the 2024 Annual Report and Accounts, which took effect immediately after the end of the AGM. The votes were cast as follows:

For			Against			Abstain
203,397,251			16,925,364			61,884

Resolution 4: To re-appoint Ernst & Young LLP as auditors of the Company to hold office from the conclusion of the 2025 AGM until the conclusion of the 2026 AGM and to authorize the Directors to determine the auditors’ remuneration. The votes were cast as follows:

For			Against			Abstain
220,272,345			110,231			1,923

Resolution 5: To re-elect Dr. R Iannone as a Director. The votes were cast as follows:

For			Against			Abstain
199,042,000			20,750,286			232,213

Resolution 6: To re-elect Dr. R Rao as a Director. The votes were cast as follows:

For			Against			Abstain
219,956,853			194,729			232,197

Resolution 7: To approve the Autolus Therapeutics plc Employee Share Purchase Plan with Sharesave Sub-Plan adopted by the Board on 20 May 2025 (the “Purchase Plan”), with 3,000,000 (three million) Shares (as defined therein) available for issuance under the Purchase Plan, and with the directors authorized to do all acts and things as are or may be necessary or expedient to carry the same into effect, notwithstanding that the directors may be interested in the same. The votes were cast as follows:

For			Against			Abstain
219,651,874			706,780			25,845

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

						AUTOLUS THERAPEUTICS PLC
Dated: June 27, 2025			By:			/s/Christian Itin, Ph.D.
						Name: Christian Itin, Ph.D.
						Title: Chief Executive Officer

FAQ

How many Autolus (AUTL) ADSs are covered by Prospectus Supplement No. 2?

Up to 54,584,250 ADSs may be resold by selling securityholders, including 3,265,306 ADSs issuable upon warrant exercise.

Does Autolus raise capital from this registration?

No. All ADSs are being sold by existing holders; the company will not receive any proceeds.

What was the shareholder approval level for the FY 2024 financial statements?

Resolution 1 received 219,809,664 votes for and 97,503 against, passing easily.

Was the Directors’ remuneration policy approved at the 2025 AGM?

Yes. It passed with 203,397,251 votes for and 16,925,364 against.

How many shares are reserved under the new Employee Share Purchase Plan?

The plan authorizes 3,000,000 ordinary shares for future issuance.