Korro Bio, Inc.
KRRO evidence brief
What we can confirm
- BioSniper Score:
- 1.5 / 10
- Market Cap:
- $203.4M
What it means
What to watch
Prepared research question
What matters most for KRRO—catalysts, financial risk and supporting evidence?
Traceable citations · Unknowns marked
BioSniper AI · KRRO
Korro Bio, Inc. (KRRO) is a clinical-stage biopharmaceutical company developing RNA-editing genetic medicines for rare diseases, with its lead program KRRO-121 in Phase 1/2 trials for urea cycle disorders and a preclinical pipeline including Alpha-1 Antitrypsin Deficiency and ALS programs.
Key risk: Limited cash runway
BioSniper Score
Based on 2 of 6 signals
Limited data coverage
Market Cap
$203.4M
Cash Runway
—
Lead Asset
—
Next Catalyst
—
Financial data as of Jun 30, 2026.
Tracking 2 clinical trials for Korro Bio, Inc..
Korro Bio, Inc. (KRRO) is a clinical-stage biopharmaceutical company developing RNA-editing genetic medicines for rare diseases, with its lead program KRRO-121 in Phase 1/2 trials for urea cycle disorders and a preclinical pipeline including Alpha-1 Antitrypsin Deficiency and ALS programs.
- Korro Bio is a clinical-stage biopharmaceutical company leveraging its oligonucleotide promoted editing of RNA (OPERA®) platform to develop genetic medicines for rare and highly prevalent diseases [news · published 2026-10-05].
- As of 2026-06-30, the company reported cash & equivalents of $24.9M, zero revenue, and a net loss of -$18.9M [sec].
- The lead program, KRRO-121, is a GalNAc-conjugated RNA-editing oligonucleotide in Phase 1/2 clinical trial (ANCHOR) for hyperammonemia in patients with urea cycle disorders; the first cohort of healthy volunteers was dosed in October 2026 [sec · filed 2026-10-05].
- Korro Bio added KRRO-111 to its pipeline in May 2026 for the potential treatment of Alpha-1 Antitrypsin Deficiency [sec · filed 2026-05-19].
- The company has a preclinical program for Amyotrophic lateral sclerosis (ALS) aiming to create a de novo variant of TDP-43 [pipeline].
What works
- Korro Bio has initiated a Phase 1/2 clinical trial (ANCHOR) for its lead candidate KRRO-121, with the first cohort dosed in October 2026, demonstrating progress toward clinical validation [sec · filed 2026-10-05].
- The company's OPERA® platform enables RNA editing via endogenous ADAR, which may allow for precise genetic correction without permanent DNA changes [news · published 2026-10-05].
- Korro Bio has a diversified pipeline including KRRO-110 (Phase 1/2 for AATD), KRRO-111 (added in May 2026), and a preclinical ALS program, spreading development risk across multiple indications [pipeline].
What to weigh
- Korro Bio reported zero revenue and a net loss of -$18.9M as of 2026-06-30, with cash & equivalents of only $24.9M, indicating a limited cash runway for ongoing operations [sec].
- The lead program KRRO-121 is still in early Phase 1/2 testing, with patient dosing not expected until the first half of 2027 and an interim readout in the second half of 2027, meaning no near-term data to validate the platform [news · published 2026-10-05].
- The company faces a highly competitive landscape for its AATD program, with 29 competitors including Arrowhead Pharmaceuticals and Grifols Therapeutics in Phase 2 [pipeline].
- The ALS program is preclinical, with 141 competitors already in later stages, making it a high-risk, long-term bet [pipeline].
From the filings
Quoted directly from source documents.
Korro Bio dosed the first cohort in its Phase 1/2 trial for KRRO-121 in October 2026.
“On October 5, 2026, Korro Bio, Inc. issued a press release announcing that it has dosed the first cohort of participants in ANCHOR, its Phase 1/2 clinical trial of KRRO-121”
SEC filings · October 5, 2026
Korro Bio's pipeline includes a preclinical ALS program.
“Pipeline Candidate: als program Indication: Amyotrophic lateral sclerosis (ALS) Phase: Preclinical”
Pipeline
Korro Bio added KRRO-111 for AATD in May 2026.
“On May 19, 2026, Korro Bio, Inc. issued a press release announcing the addition of KRRO-111 for the potential treatment of Alpha-1 Antitrypsin Deficiency to its pipeline”
SEC filings · May 19, 2026
Catalyst timeline
- 2025-01-13 · Phase2_Start: A Phase 1/2a, Single- and Multiple-dose Escalation Study to Evaluate the Safety, Tolerability, Pharmacodynamics, and Pharmacokinetics of KRRO 110 in Healthy Adult Volunteers and in Adult Participants With Alpha-1 Antitrypsin Deficiency (AATD) (REWRITE) — Initiation of Phase 1/2a trial for KRRO-110 in AATD; watch for early safety and PK/PD data.
- 2026-09-28 · Phase2_Start: A Phase 1/2, Randomized, Double-Blind, Placebo-Controlled, Single- and Multiple-Ascending Dose Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of KRRO-121 in Healthy Volunteers and Patients With Urea Cycle Disorders — Initiation of Phase 1/2 trial for KRRO-121; watch for dosing updates and interim results.
Risks & what to watch (4)›
Key risks
- Limited cash runway — Cash & equivalents of $24.9M as of 2026-06-30 with zero revenue and ongoing losses may only support operations for a short period [sec].
- Early-stage lead program — KRRO-121 is in Phase 1/2 with patient dosing not expected until H1 2027 and interim data in H2 2027, so no near-term validation [news · published 2026-10-05].
- Intense competition in AATD — The AATD space has 29 competitors, including Arrowhead Pharmaceuticals and Grifols Therapeutics in Phase 2 [pipeline].
- Preclinical ALS program — The ALS program is preclinical with 141 competitors in later stages, making it a high-risk, long-term endeavor [pipeline].
What to watch
- Interim readout from the KRRO-121 Phase 1/2 trial expected in the second half of 2027 [news · published 2026-10-05].
- Initiation of patient dosing in the KRRO-121 trial, expected in the first half of 2027 [news · published 2026-10-05].
- Progress of the KRRO-110 Phase 1/2a trial for AATD, which started in January 2025 [catalyst].
- Any updates on the preclinical ALS program and potential IND filings [pipeline].
Sources: Catalysts · News · Pipeline · SEC filings · Generated October 10, 2026 · How we verify sources →
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Evidence & data
Score breakdownBased on 2 of 6 signals · derived from public data
Pipeline inputs are unavailable for this score. It uses only the available signals shown below.
Cash runway data unavailable
Net income -$19M
No tracked pipeline phase
No tracked pipeline candidates
No upcoming catalysts tracked
2 buys · 26 sells (180d)
Regulatory
Financials
Institutional Holdings
Source: SEC Form 13F · as of Mar 2026Institutional holders
98
Total value held
$144.0M
| Holder | Shares | Value |
|---|---|---|
| lynx1 capital management lp | 1,538,296 | $17.4M |
| nea management company, llc | 1,297,893 | $14.7M |
| atlas venture life science advisors, llc | 1,137,149 | $12.9M |
| balyasny asset management l.p. | 1,040,054 | $11.8M |
| venrock adviser, llc | 1,009,500 | $11.4M |
| affinity asset advisors, llc | 706,904 | $8.0M |
| nantahala capital management, llc | 660,036 | $7.5M |
| adar1 capital management, llc | 540,054 | $6.1M |
| blackrock, inc. | 460,006 | $5.2M |
| driehaus capital management llc | 450,045 | $5.1M |
Showing top 10 of 98 institutional holders of Korro Bio, Inc.. Open the full 13F history after sign-in.
Short Interest
as of May 21, 2026- % of float
- 8.7%
- Days to cover
- 7.3
- Shares short
- 1,117,429
- Daily short volume
- -
Short percent of float and days-to-cover reflect reported short positioning. Daily short volume is the exchange-reported short share of a single day's trading volume and is noisier. See the most-shorted biotech ranking →
KRRO short interestGovernance
Frequently asked questions
What is the AI investment thesis for Korro Bio, Inc.?
Korro Bio, Inc. (KRRO) is a clinical-stage biopharmaceutical company developing RNA-editing genetic medicines for rare diseases, with its lead program KRRO-121 in Phase 1/2 trials for urea cycle disorders and a preclinical pipeline including Alpha-1 Antitrypsin Deficiency and ALS programs.
Who is the CEO of Korro Bio, Inc.?
Dr. Ram Aiyar MBA, Ph.D. is the chief executive officer of Korro Bio, Inc. (KRRO).
Where is Korro Bio, Inc. headquartered?
Korro Bio, Inc. (KRRO) is headquartered in Cambridge, MA, United States.
What therapeutic areas does Korro Bio, Inc. focus on?
Korro Bio, Inc. develops therapies across Neurology.
The AI overview and BioSniper Score are neutral, data-derived signals built from public SEC filings, ClinicalTrials.gov and FDA records — not investment advice.