8-K

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): January 15, 2026

Korro Bio, Inc.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (617)

468-1999

N/A

(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:

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

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 8.01. Other Events.

On January 15, 2026, Korro Bio, Inc. updated its corporate presentation for use in meetings with investors, analysts and others. A copy of certain updated slides is filed as Exhibit 99.1 to this current report on Form 8-K and is incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

SIGNATURES

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

Forward-Looking Statement and Disclaimers Forward-Looking Statements Certain statements in this presentation may constitute “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking statements include, but are not limited to, express or implied statements regarding expectations, hopes, beliefs, intentions or strategies of Korro Bio, Inc. (Korro) regarding the future including, without limitation, express or implied statements regarding: Korro’s ability to activate a biological pathways with RNA editing; Korro’s ability to create value in 2026 and beyond; Korro’s cash runway and uses thereof; the timing of and ability to submit a regulatory filing for KRRO-121; the market opportunity for KRRO-121; the potential of Korro’s GalNAC-conjugated programs targeting the liver, including KRRO-121 and GalNAc delivery for AATD patients; and timing of nominating a development candidate for Korro’s GalNAc-conjugated program for AATD. In addition, any statements that refer to projections, forecasts, or other characterizations of future events or circumstances, including any underlying assumptions, are forward-looking statements. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “strive,” “would,” “aim,” “target,” “commit,” and similar expressions may identify forward-looking statements, but the absence of these words does not mean that statement is not forward looking. Forward-looking statements are based on current expectations and assumptions that, while considered reasonable are inherently uncertain. New risks and uncertainties may emerge from time to time, and it is not possible to predict all risks and uncertainties. Factors that may cause actual results to differ materially from current expectations include, but are not limited to, various factors beyond management’s control including risks inherent in biopharmaceutical development; risks associated with pre-clinical studies and clinical studies; and other risks associated with obtaining regulatory approvals and protecting intellectual property; as well as risks associated with general economic conditions; the possibility that Korro may be adversely affected by other economic, business, and/or competitive factors; other risks and uncertainties indicated from time to time in Korro’s filings with the SEC, including Item 1A. “Risk Factors” in Korro’s most recent Quarterly Report on Form 10-K or Form 10-Q filed with the SEC, as such may be amended or supplemented by its other filings with the SEC. Nothing in this presentation should be regarded as a representation by any person that the forward-looking statements set forth herein will be achieved or that any of the contemplated results of such forward-looking statements will be achieved. You should not place undue reliance on forward-looking statements in this presentation, which speak only as of the date they are made and are qualified in their entirety by reference to the cautionary statements herein. Except as required by law, Korro does not undertake or accept any duty to release publicly any updates or revisions to any forward-looking statements to reflect any change in their expectations or in the events, conditions or circumstances on which any such statement is based. This presentation does not purport to summarize all of the conditions, risks and other attributes of an investment in Korro. Industry and Market Data Certain information contained in this presentation relates to or is based on studies, publications, surveys and Korro’s own internal estimates and research. In this presentation, Korro relies on, and refers to, publicly available information and statistics regarding market participants in the sector in which Korro competes and other industry data. Any comparison of Korro to any other entity assumes the reliability of the information available to Korro. Korro obtained this information and statistics from third-party sources, including reports by market research firms and company filings. In addition, all of the market data included in this presentation involve a number of assumptions and limitations, and there can be no guarantee as to the accuracy or reliability of such assumptions. Finally, while Korro believes its internal research is reliable, such research has not been verified by any independent source and Korro has not independently verified the information. Trademarks This presentation may contain trademarks, service marks, trade names and copyrights of Korro or other third parties, which are the property of their respective owners. Solely for convenience, some of the trademarks, service marks, trade names and copyrights referred to in this presentation may be listed without the TM, SM © or ® symbols, but Korro will assert, to the fullest extent under applicable law, the rights of the applicable owners, if any, to its trademarks, service marks, trade names and copyrights. Exhibit 99.1

CONCEPT PROGRAM / INDICATION DELIVERY DISCOVERY PRECLINICALDEVELOPMENT PHASE 1 PHASE 2 PHASE 3 Stabilize Protein KRRO-121 Hyperammonemia GalNAc (SC) Repair Pathogenic Variant AATD GalNAc (SC) Allosteric Activator Longevity (Liver) GalNAc (SC) Overcome LoF and GoF 1 Amyotrophic lateral sclerosis (ALS) Intrathecal (IT) Reg filing in 2H 2026 TDP43 Pipeline with Potential High-Value Programs and Anticipated Milestones 1De Novo protein variant to prevent toxic gain of function (GoF) with TDP43 aggregation, and continue downstream signaling by overcoming toxic Loss-of-function (LOF) Novo Nordisk collaboration entered 12-month pause in Nov. 2025 AAT DC in 1H 2026 Terminating the REWRITE clinical trial for KRRO-110 in AATD AMPK𝛾1 Protein variant creation Protein repair