KORRO BIO INC KRRO
COM · Common Stock · CUSIP 500946108
- SectorHealth care
- IndustryPharmaceutical Preparations
- HeadquartersCambridge, MA
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($74.8k this quarter). Holder counts are more reliable. Shares outstanding: 14.7m as of 2026-08-05, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $13.18. Options: 4 managers hold calls ($1.4m notional), 3 hold puts ($539.1k).
Trends to Q2 2026
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q4 2023 | 41 |
| Q1 2024 | 50 |
| Q2 2024 | 64 |
| Q3 2024 | 72 |
| Q4 2024 | 85 |
| Q1 2025 | 76 |
| Q2 2025 | 72 |
| Q3 2025 | 92 |
| Q4 2025 | 83 |
| Q1 2026 | 99 |
| Q2 2026 | 107 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q3 2024 | 34 | 21 |
| Q4 2024 | 52 | 23 |
| Q1 2025 | 31 | 41 |
| Q2 2025 | 36 | 28 |
| Q3 2025 | 55 | 25 |
| Q4 2025 | 44 | 52 |
| Q1 2026 | 62 | 35 |
| Q2 2026 | 67 | 30 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q3 2025 | $0 | $0 | — |
| Q4 2025 | $162.6k | $7.9m | 48.78 |
| Q1 2026 | $1.8m | $3.7m | 2.08 |
| Q2 2026 | $1.4m | $539.1k | 0.40 |
Biggest buyers
| Nantahala Capital Management, LLC | Added | +660.0k |
| BlackRock, Inc. | Added | +357.6k |
| ADAGE CAPITAL PARTNERS GP, L.L.C. | Added | +312.6k |
| Kalehua Capital Management LLC | Added | +295.7k |
| VANGUARD CAPITAL MANAGEMENT LLC | Added | +143.9k |
| GEODE CAPITAL MANAGEMENT, LLC | Added | +123.2k |
| STATE STREET CORP | Added | +92.2k |
| UBS Group AG | Added | +83.8k |
| VANGUARD PORTFOLIO MANAGEMENT LLC | Added | +75.0k |
| GOLDMAN SACHS GROUP INC | Added | +66.4k |
Biggest sellers
| Atlas Venture Life Science Advisors, LLC | Reduced | -174.3k |
| JANE STREET GROUP, LLC | Sold out | -115.7k |
| Balyasny Asset Management L.P. | Reduced | -88.3k |
| Trexquant Investment LP | Reduced | -44.7k |
| ACADIAN ASSET MANAGEMENT LLC | Reduced | -27.3k |
| RENAISSANCE TECHNOLOGIES LLC | Reduced | -25.7k |
| Quadrature Capital Ltd | Sold out | -20.4k |
| MORGAN STANLEY | Reduced | -18.6k |
| MARSHALL WACE, LLP | Reduced | -15.3k |
| Engineers Gate Manager LP | Reduced | -13.5k |
Biggest calls
| CITADEL ADVISORS LLC | Added | $935.8k71.0k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | $383.5k29.1k shares |
| SIMPLEX TRADING, LLC | Added | $26.4k2.0k shares |
| GROUP ONE TRADING LLC | Reduced | $7.9k600 shares |
Biggest puts
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | $239.9k18.2k shares |
| CITADEL ADVISORS LLC | Reduced | $163.4k12.4k shares |
| SIMPLEX TRADING, LLC | Added | $135.8k10.3k shares |
Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
| Lynx1 Capital Management LP 13G · passive investor +2.9 pts · filed 2026-04-02 | 10.7% |
| Venrock Healthcare Capital Partners III, L.P. 13G · passive investor new · filed 2026-03-17 | 9.9% |
New Enterprise Associates 17, L.P.
13D · may seek influence
filed 2026-03-12
Stated purposeNEA 17 acquired the NEA 17 Shares for investment purposes. Information with respect to the 2026 Private Placement set forth in Item 3 above is incorporated herein by reference to the extent responsive to this Item 4. Subject to the Registration Rights Agreement, the 2024 Registration Rights Agreement and the 2026 Registration Rights Agreement (as defined below) and depending on market conditions, its continuing evaluation of the business and prospects of the Issuer and other factors, NEA 17 and the other Reporting Persons may dispose of or acquire additional shares of the Issuer. Except as set forth above, none of the Reporting Persons has any present plans which relate to or would result in: (a) The acquisition by any person of additional securities of the Issuer, or the disposition of … Full filing |
9.9% |
| BALYASNY ASSET MANAGEMENT L.P. 13G · institution filed 2026-08-14 | 6.6% |
| Nantahala Capital Management, LLC 13G · institution new · filed 2026-02-13 | 6.4% |
Fell to 5% or below in the last year: BlackRock, Inc. (4.9%, 2026-10-27), Atlas Venture Fund XI, L.P. (4.9%, 2026-08-04), Point72 Asset Management, L.P. (1.9%, 2026-05-15), VANGUARD GROUP INC (0.0%, 2026-03-27), DRIEHAUS CAPITAL MANAGEMENT LLC (0.0%, 2026-02-17), FMR LLC (0.4%, 2026-02-05)
Insider purchases and sales since 1 Apr 2026
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q4 2024 | 0 | — | 1 | $855.5k | $855.5k |
| Q1 2025 | 0 | — | 0 | — | — |
| Q2 2025 | 0 | — | 0 | — | — |
| Q3 2025 | 0 | — | 0 | — | — |
| Q4 2025 | 0 | — | 0 | — | — |
| Q1 2026 | 0 | — | 0 | — | — |
| Q2 2026 | 0 | — | 6 | $2.9m | $2.5m |
| Q3 2026 | 0 | — | 3 | $2.8m | $2.8m |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2026-09-14 | FORMELA JEAN FRANCOIS Director · See footnote | Sold plan | $543.5k38.5k shares |
| 2026-09-11 | FORMELA JEAN FRANCOIS Director · See footnote | Sold plan | $142.7k10.2k shares |
| 2026-09-11 | Dolan Oliver Senior Vice President, Finance | Sold plan | $695 shares |
| 2026-09-09 | Dolan Oliver Senior Vice President, Finance | Sold plan | $826 shares |
| 2026-09-08 | Dolan Oliver Senior Vice President, Finance | Sold plan | $99.3k7.3k shares |
| 2026-08-26 | FORMELA JEAN FRANCOIS Director · See footnote | Sold plan | $4.2k300 shares |
| 2026-08-19 | FORMELA JEAN FRANCOIS Director · See footnote | Sold plan | $398.6k28.5k shares |
| 2026-08-11 | FORMELA JEAN FRANCOIS Director · See footnote | Sold plan | $29.9k2.1k shares |
| 2026-08-10 | Nichols Weston +1 10% owner · See footnote | Bought | $19.3k1.5k shares |
| 2026-08-06 | Nichols Weston +1 10% owner · See footnote | Bought | $59.5k5.2k shares |
| 2026-08-04 | Aiyar Ram President and CEO, director | Sold | $62.9k5.8k shares |
| 2026-07-06 | FORMELA JEAN FRANCOIS Director · See footnote | Sold plan | $130.1k9.3k shares |
| 2026-07-02 | FORMELA JEAN FRANCOIS Director · See footnote | Sold plan | $1.4m100.7k shares |
| 2026-06-24 | FORMELA JEAN FRANCOIS Director · See footnote | Sold plan | $707.5k48.4k shares |
| 2026-06-23 | FORMELA JEAN FRANCOIS Director · See footnote | Sold plan | $1.7m119.0k shares |
| 2026-06-22 | FORMELA JEAN FRANCOIS Director · See footnote | Sold plan | $55.3k4.0k shares |
| 2026-06-16 | Cerio Jeffrey General Counsel | Sold | $71.6k6.6k shares |
| 2026-06-16 | Vincent Loic A Chief Scientific Officer | Sold | $37.0k3.4k shares |
| 2026-06-16 | Dolan Oliver Senior Vice President, Finance | Sold | $36.6k3.4k shares |
| 2026-06-16 | Chappell Todd Chief Operating Officer | Sold | $34.3k3.2k shares |
| 2026-05-29 | Aiyar Ram President and CEO, director | Sold | $196.7k15.2k shares |
| 2026-05-28 | FORMELA JEAN FRANCOIS Director · See footnote | Sold plan | $39.9k2.9k shares |
Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).
Holders, Q2 2026
| Manager | Shares | Change |
|---|---|---|
| Lynx1 Capital Management LP 2.34% of their portfolio | 1.5m $20.3m | Unchanged |
| Nantahala Capital Management, LLC 0.53% of their portfolio | 1.3m $17.4m | Added +660.0k |
| NEA Management Company, LLC 1.08% of their portfolio | 1.3m $17.1m | Unchanged |
| Venrock Adviser, LLC 0.40% of their portfolio | 1.0m $13.3m | Unchanged |
| Atlas Venture Life Science Advisors, LLC 1.44% of their portfolio | 962.9k $12.7m | Reduced -174.3k |
| Balyasny Asset Management L.P. 0.02% of their portfolio | 951.8k $12.5m | Reduced -88.3k |
| BlackRock, Inc. 0.00% of their portfolio | 817.6k $10.8m | Added +357.6k |
| Affinity Asset Advisors, LLC 0.46% of their portfolio | 706.9k $9.3m | Unchanged |
| ADAGE CAPITAL PARTNERS GP, L.L.C. 0.01% of their portfolio | 541.0k $7.1m | Added +312.6k |
| ADAR1 Capital Management, LLC 0.33% of their portfolio | 540.1k $7.1m | Unchanged |
| VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 454.8k $6.0m | Added +143.9k |
| Driehaus Capital Management LLC 0.03% of their portfolio | 450.0k $5.9m | Unchanged |
| TCG Crossover Management, LLC 0.13% of their portfolio | 416.3k $5.5m | Unchanged |
| Kalehua Capital Management LLC 1.70% of their portfolio | 405.0k $5.3m | Added +295.7k |
| Siren, L.L.C. 0.09% of their portfolio | 347.7k $4.6m | Unchanged |
| AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 299.0k $3.9m | Added +31.2k |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 296.9k $3.9m | Added +123.2k |
| 72 Investment Holdings, LLC 7.30% of their portfolio | 276.8k $3.6m | Unchanged |
| STATE STREET CORP 0.00% of their portfolio | 232.6k $3.1m | Added +92.2k |
| VANGUARD PORTFOLIO MANAGEMENT LLC 0.00% of their portfolio | 223.6k $2.9m | Added +75.0k |
| TWO SIGMA INVESTMENTS, LP 0.00% of their portfolio | 178.1k $2.3m | Added +12.6k |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 124.7k $1.6m | Added +56.2k |
| MILLENNIUM MANAGEMENT LLC 0.00% of their portfolio | 118.4k $1.6m | Added +54.8k |
| GOLDMAN SACHS GROUP INC 0.00% of their portfolio | 117.0k $1.5m | Added +66.4k |
| RENAISSANCE TECHNOLOGIES LLC 0.00% of their portfolio | 110.5k $1.5m | Reduced -25.7k |
| UBS Group AG 0.00% of their portfolio | 105.5k $1.4m | Added +83.8k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 88.1k $1.2m | Added +30.4k |
| VANGUARD FIDUCIARY TRUST CO 0.00% of their portfolio | 74.9k $987.2k | Added +33.4k |
| EMERALD MUTUAL FUND ADVISERS TRUST 0.03% of their portfolio | 63.6k $837.7k | Added +707 |
| F/m Investments LLC 0.04% of their portfolio | 63.6k $837.7k | Added +707 |
| Walleye Capital LLC 0.00% of their portfolio | 54.3k $715.5k | New |
| Quantinno Capital Management LP 0.00% of their portfolio | 52.7k $694.9k | Added +16.7k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 51.7k $681.5k | New |
| RAYMOND JAMES FINANCIAL INC 0.00% of their portfolio | 48.9k $644.8k | Added +6.1k |
| XTX Topco Ltd 0.01% of their portfolio | 47.8k $630.3k | Reduced -12.7k |
| CITADEL ADVISORS LLC 0.00% of their portfolio | 40.4k $532.3k | Added +9.5k |
| FMR LLC 0.00% of their portfolio | 39.0k $513.7k | Added +75 |
| BOOTHBAY FUND MANAGEMENT, LLC 0.01% of their portfolio | 35.9k $472.5k | Reduced -6.1k |
| D. E. Shaw & Co., Inc. 0.00% of their portfolio | 34.2k $450.9k | New |
| Jump Financial, LLC 0.00% of their portfolio | 33.9k $446.9k | New |
| Bank of New York Mellon Corp 0.00% of their portfolio | 31.7k $418.2k | Added +10.0k |
| AIHC Capital Management Ltd 0.38% of their portfolio | 30.3k $398.9k | Unchanged |
| Mariner, LLC 0.00% of their portfolio | 27.9k $367.8k | Added +2.1k |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 26.3k $346.0k | Added +23.9k |
| PANAGORA ASSET MANAGEMENT INC 0.00% of their portfolio | 25.6k $337.0k | New |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 24.1k $317.8k | Added +10.7k |
| MORGAN STANLEY 0.00% of their portfolio | 22.5k $296.6k | Reduced -18.6k |
| IEQ CAPITAL, LLC 0.00% of their portfolio | 21.2k $280.0k | Added +8.5k |
| MARSHALL WACE, LLP 0.00% of their portfolio | 19.1k $251.2k | Reduced -15.3k |
| GUGGENHEIM CAPITAL LLC 0.00% of their portfolio | 18.4k $242.5k | Added +4.3k |
| HSBC HOLDINGS PLC 0.00% of their portfolio | 17.8k $232.8k | New |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 17.6k $233.0k | New |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 15.9k $210.2k | Added +5.4k |
| Nuveen, LLC 0.00% of their portfolio | 15.9k $209.0k | New |
| ACADIAN ASSET MANAGEMENT LLC 0.00% of their portfolio | 14.5k $189.0k | Reduced -27.3k |
| ALGERT GLOBAL LLC 0.00% of their portfolio | 14.2k $187.3k | Reduced -5.0k |
| Susquehanna Portfolio Strategies, LLC 0.00% of their portfolio | 13.5k $177.9k | Reduced -5.6k |
| MERCER GLOBAL ADVISORS INC /ADV 0.00% of their portfolio | 12.9k $169.9k | New |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 12.4k $163.4k | Added +2.6k |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 12.2k $137.9k | New |
| WEALTH ENHANCEMENT ADVISORY SERVICES, LLC 0.00% of their portfolio | 11.5k $167.6k | New |
| Trexquant Investment LP 0.00% of their portfolio | 11.5k $151.3k | Reduced -44.7k |
| DIMENSIONAL FUND ADVISORS LP 0.00% of their portfolio | 11.4k $150.3k | New |
| Cerity Partners LLC 0.00% of their portfolio | 10.8k $142.3k | New |
| Engineers Gate Manager LP 0.00% of their portfolio | 10.2k $134.7k | Reduced -13.5k |
| AMERICAN CENTURY COMPANIES INC 0.00% of their portfolio | 10.2k $133.8k | New |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 9.6k $126.1k | Added +7.0k |
| Arax Advisory Partners 0.00% of their portfolio | 5.6k $73.7k | Added +5.5k |
| CITIGROUP INC 0.00% of their portfolio | 5.2k $68.1k | Added +4.9k |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio | 5.1k $67.6k | Added +1.9k |
| Russell Investments Group, Ltd. 0.00% of their portfolio | 4.9k $65.1k | Added +2.8k |
| Police & Firemen's Retirement System of New Jersey 0.00% of their portfolio | 4.6k $61.0k | Added +3.3k |
| NEW YORK STATE COMMON RETIREMENT FUND 0.00% of their portfolio | 3.0k $39.5k | Unchanged |
| SIMPLEX TRADING, LLC 0.00% of their portfolio | 2.0k $26.0k | New |
| Vanguard Global Advisers, LLC 0.00% of their portfolio | 1.9k $25.4k | Unchanged |
| North Star Investment Management Corp. 0.00% of their portfolio | 1.8k $23.7k | Unchanged |
| Tower Research Capital LLC (TRC) 0.00% of their portfolio | 1.6k $20.9k | Reduced -57 |
| Integrated Wealth Concepts LLC 0.00% of their portfolio | 1.6k $20.9k | New |
| Legal & General Group Plc 0.00% of their portfolio | 1.1k $14.3k | Added +556 |
| GAMMA Investing LLC 0.00% of their portfolio | 861 $11.3k | Added +124 |
| TD Waterhouse Canada Inc. 0.00% of their portfolio | 808 $11.0k | Unchanged |
| Ameritas Investment Partners, Inc. 0.00% of their portfolio | 598 $7.9k | Unchanged |
| Versant Capital Management, Inc 0.00% of their portfolio | 539 $7.1k | Reduced -152 |
| Allworth Financial LP 0.00% of their portfolio | 538 $7.1k | Added +247 |
| EverSource Wealth Advisors, LLC 0.00% of their portfolio | 498 $6.6k | Added +119 |
| DUNCKER STREETT & CO INC 0.00% of their portfolio | 437 $5.8k | Unchanged |
| IFP Advisors, Inc 0.00% of their portfolio | 418 $5.5k | Added +373 |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 352 $4.0k | Added +248 |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.00% of their portfolio | 225 $3.0k | Unchanged |
| PNC Financial Services Group, Inc. 0.00% of their portfolio | 193 $2.5k | Reduced -637 |
| True Wealth Design, LLC 0.00% of their portfolio | 192 $2.5k | Added +93 |
| Sterling Capital Management LLC 0.00% of their portfolio | 191 $2.5k | Reduced -29 |
| Essential Partners LLC 0.00% of their portfolio | 180 $2.4k | Reduced -1.1k |
| OSAIC HOLDINGS, INC. 0.00% of their portfolio | 134 $1.8k | Reduced -1 |
| ROTHSCHILD INVESTMENT LLC 0.00% of their portfolio | 123 $1.6k | Added +51 |
| Farther Finance Advisors, LLC 0.00% of their portfolio | 115 $1.5k | Added +61 |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 93 $1.2k | New |
| Optiver Holding B.V. 0.00% of their portfolio | 60 $791 | Unchanged |
| Basecamp Wealth Advisors LLC 0.00% of their portfolio | 45 $593 | Added +20 |
| Timbuktu Capital Management, LLC 0.00% of their portfolio | 38 $501 | First filing |