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): August 18, 2026

MEREO BIOPHARMA GROUP PLC

(Exact name of registrant as specified in its charter)

4th Floor, One Cavendish Place,

London, W1G 0QF

United Kingdom

(Address of principal executive offices, including zip code)

+44-333-023-7300

(Registrant’s telephone number, including area code)

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:

*Not for trading, but only in connection with the listing of the American Depositary Shares on The Nasdaq Stock Market LLC.

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 3.01 - Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

As previously disclosed, on February 17, 2026, Mereo BioPharma Group plc (the “Company”) received a written notice (the “First Notice”) from the Listing Qualifications Department (the “Staff”) of The Nasdaq Stock Market LLC (“Nasdaq”) indicating that it no longer met the requirement to maintain a minimum bid price of $1.00 per share for continued listing on The Nasdaq Capital Market (the “Capital Market”) under Nasdaq Listing Rule 5550(a)(2) (the “Bid Price Requirement”). In accordance with Nasdaq Listing Rule 5810(c)(3)(A), the Company was provided an initial period of 180 calendar days, or until August 17, 2026, to regain compliance with the Bid Price Requirement.

On August 18, 2026, the Company received a second notice (the “Second Notice”) from the Staff indicating that, while the Company has not yet regained compliance with the Bid Price Requirement, the Company is eligible for an additional 180 calendar day period, or until February 16, 2027 (the “Second Compliance Period”), to regain compliance.

If at any time during the Second Compliance Period, the closing bid price of the Company’s American Depositary Shares (“ADSs”) is at least $1.00 per share for a minimum of 10 consecutive business days, the Staff will provide the Company written confirmation of compliance. If the Company does not regain compliance by the end of the Second Compliance Period, the Staff will provide written notice that the Company’s securities will be delisted. At that time, the Company may appeal the delisting determination to a Nasdaq Hearings Panel. There can be no assurance that the Company will regain compliance or otherwise maintain compliance with any of the other listing requirements.

The First Notice and the Second Notice have no immediate effect on the listing of the Company’s ADSs on the Capital Market. The Company intends to continue to monitor the closing bid price of its ADSs and may, if appropriate, consider available options to regain compliance with the Bid Price Requirement.

Forward Looking Statements

This Current Report on Form 8-K contains “forward-looking statements.” All statements other than statements of historical fact contained herein are forward-looking statements within the meaning of Section 27A of the Securities Act, and Section 21E of the Exchange Act. Forward-looking statements usually relate to future events and anticipated revenues, earnings, cash flows or other aspects of the Company’s operations or operating results. Forward-looking statements are often identified by the words “believe,” “expect,” “anticipate,” “plan,” “intend,” “foresee,” “should,” “would,” “could,” “may,” “estimate,” “outlook,” “will,” “continue” and similar expressions, including the negative thereof. The absence of these words, however, does not mean that the statements are not forward-looking. These forward-looking statements are based on Mereo’s current expectations, beliefs and assumptions concerning future developments and business conditions and their potential effect on Mereo. While management believes that these forward-looking statements are reasonable as and when made, there can be no assurance that future developments affecting Mereo will be those that it anticipates. All of Mereo’s forward-looking statements involve known and unknown risks and uncertainties some of which are significant or beyond its control and assumptions that could cause actual results to differ materially from Mereo’s historical experience and its present expectations or projections. Such risks and uncertainties include, among others, the uncertainties inherent in the clinical development process; Mereo’s reliance on third parties to conduct and provide funding for its clinical trials; the sufficiency of existing cash to fund operations and/or the inability to raise additional funding on favorable terms or at all; the uncertainty inherent in regulatory review processes, including varying interpretations and analyses of data from clinical trials; Mereo’s dependence on enrollment of patients in its clinical trials; potentially smaller than anticipated market opportunities for Mereo’s product candidates; Mereo’s dependence on its key executives; the Company’s dependence on its strategic partners; and the Company’s ability to maintain compliance with Nasdaq continued listing requirements. You should carefully consider the foregoing factors and the other risks and uncertainties that affect Mereo’s business, including those described in the “Risk Factors” section of its latest Annual Report on Form 10-K, as well as discussions of potential risks, uncertainties, and other important factors in Mereo’s subsequent filings with the Securities and Exchange Commission. Mereo wishes to caution you not to place undue reliance on any forward-looking statements, which speak only as of the date hereof. Mereo undertakes no obligation to publicly update or revise any of our forward-looking statements after the date they are made, whether as a result of new information, future events or otherwise, except to the extent required by law.

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.