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Baker Bros sets 49.9% voting cap in Kiniksa (NASDAQ: KNSA)

(Moderate)
(Neutral)
Form Type
SCHEDULE 13D/A

Rhea-AI Filing Summary

Baker Bros. Advisors and related entities filed Amendment No. 6 to their Schedule 13D for Kiniksa Pharmaceuticals International, plc, reporting beneficial ownership of about 7% of Kiniksa’s Class A ordinary shares. Their percentages are based on 46,303,276 Class A shares outstanding as of April 24, 2026.

On May 21, 2026, Kiniksa and the Adviser signed a Deed of Waiver that limits conversions of the Funds’ Class A1 and Class B1 ordinary shares so that the Funds and certain affiliates will not exceed 49.9% of Kiniksa’s outstanding voting rights. Separate 4.99% beneficial ownership limits and 61‑day notice periods apply to conversions of Class A1 and Class B1 shares. Without these conversion limits, the Reporting Persons may be deemed beneficial owners of 32,107,763 Class A ordinary shares, or about 42.5% of the outstanding Class A shares.

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Insights

Baker Bros. formalizes caps on potential control while disclosing sizable optional ownership.

Baker Bros. Advisors and affiliates report current beneficial ownership of 3,231,181–3,253,341 Kiniksa Class A shares, or about 6.9%–7.0%, calculated on April 24, 2026 outstanding shares. This filing mainly clarifies structure, options, and conversion mechanics rather than adding new capital.

The newly disclosed Deed of Waiver restricts conversions of Class A1 and Class B1 shares so the group’s voting rights cannot exceed 49.9%. It also layers a 4.99% per-class beneficial ownership limit under Rule 13d-3, changeable only with 61 days’ notice, which constrains how quickly voting power can expand.

Without these limits, the group could be deemed to beneficially own 32,107,763 Class A shares, or about 42.5% of the class, assuming only their A1 and B1 holdings convert. Future disclosures in Kiniksa’s periodic reports and ownership statements will show whether actual ownership moves toward this theoretical level within the Deed’s constraints.

Beneficial ownership (Adviser) 3,231,181 Class A shares Baker Bros. Advisors; 6.9% of Class A
Beneficial ownership (Julian/Felix Baker) 3,253,341 Class A shares Each at 7.0% of Class A
Shares outstanding 46,303,276 Class A shares Outstanding as of April 24, 2026
Theoretical ownership without limits 32,107,763 Class A shares 42.5% of Class A if A1 and B1 convert
Voting cap in Deed of Waiver 49.9% of voting rights Maximum voting rights for Funds and affiliates
Per-class conversion cap 4.99% beneficial ownership Limit for Class A1 and B1 conversions
Vested share options (board-related) 181,591 options Exercisable for 181,591 Class A shares
Example option strike price $18.00 per share Share Options expiring May 22, 2028
Deed of Waiver regulatory
"entered into a Deed of Waiver (the "Deed") according to which the Adviser..."
beneficial ownership financial
"would beneficially own more than 49.9% of the outstanding voting rights..."
Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.
Rule 13d-3 regulatory
"would not beneficially own, for purposes of Rule 13d-3 under the Exchange Act..."
Rule 13d-3 defines who is treated as the beneficial owner of a company’s shares for U.S. securities disclosure rules — essentially anyone who has the power to vote or direct how shares are voted, or the power to buy or sell them, even if they don’t hold the certificates. For investors this matters because crossing certain ownership thresholds triggers public filing and disclosure obligations and signals potential control or influence, much like having the keys to a car implies you can drive it even if it’s registered to someone else.
restricted stock units financial
"12,546 Class A ordinary shares received from the vesting of restricted stock units..."
Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.
Share Options financial
"181,591 vested non-qualified options exercisable for 181,591 Class A ordinary shares ("Share Options")..."
Share options are contracts that give someone the right, but not the obligation, to buy a company’s stock at a predetermined price for a limited time—think of them like a coupon to purchase shares later at a set price. They matter to investors because when exercised they increase the number of outstanding shares (dilution), can change management incentives and company value, and represent a potential future claim on profits or equity.
Class A1 ordinary shares financial
"Class A1 ordinary shares of the Issuer ("Class A1 ordinary shares")..."

AI-generated analysis. How Rhea-AI works. Not financial advice.

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FAQ

What ownership stake does Baker Bros. report in Kiniksa (KNSA) in Amendment No. 6?

Baker Bros. Advisors and related reporting persons report beneficial ownership of about 3.23–3.25 million Kiniksa Class A shares, representing roughly 6.9–7.0% of the Class A ordinary shares, based on 46,303,276 shares outstanding as of April 24, 2026.

What is the Deed of Waiver disclosed in Kiniksa (KNSA) Schedule 13D/A Amendment No. 6?

The Deed of Waiver is an agreement dated May 21, 2026 under which Baker Bros.’ funds waive conversion rights that would push them above 49.9% of Kiniksa’s outstanding voting rights, and restrict transfers of Class A1 and B1 shares unless the transferee accepts similar limitations.

How do Class A1 and Class B1 shares convert in the Kiniksa (KNSA) ownership structure?

Kiniksa’s Class A1 and B1 ordinary shares are non-voting and convertible 1-for-1 into voting Class A or Class B shares without extra consideration, but only so long as the holders and certain affiliates do not exceed 4.99% beneficial ownership of Class A or other registered equity classes.

What is Baker Bros.’ potential ownership in Kiniksa (KNSA) without conversion limits?

Without the beneficial ownership and voting caps, the reporting group may be deemed beneficial owners of 32,107,763 Kiniksa Class A shares, representing approximately 42.5% of the total outstanding Class A ordinary shares, assuming only their Class A1 and Class B1 shares are converted.

What share count did Kiniksa (KNSA) use to calculate Baker Bros.’ ownership percentages?

The reported beneficial ownership percentages use 46,303,276 Kiniksa Class A ordinary shares outstanding as of April 24, 2026, as disclosed in Kiniksa’s Form 10-Q, plus certain vested options and RSUs included in the denominator for some reporting persons.

Are there recent Baker Bros. share transactions in Kiniksa (KNSA) before this 13D/A filing?

The reporting persons state that there were no transactions in Kiniksa Class A ordinary shares by them during the sixty days preceding the filing date of this Schedule 13D/A Amendment No. 6, indicating no recent trading activity in that period.





G52694109

(CUSIP Number)
Alexandra A. Toohey, CFO
860 Washington Street, 3rd Floor,
New York, NY, 10014
212-339-5690

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)
05/21/2026

(Date of Event Which Requires Filing of This Statement)


If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).




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SCHEDULE 13D






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SCHEDULE 13D


Baker Bros. Advisors LP
Signature:/s/ Scott L. Lessing
Name/Title:By: Baker Bros. Advisors (GP) LLC, its general partner Scott L. Lessing/ President
Date:05/26/2026
Baker Bros. Advisors (GP) LLC
Signature:/s/ Scott L. Lessing
Name/Title:Scott L. Lessing/ President
Date:05/26/2026
Julian C. Baker
Signature:/s/ Julian C. Baker
Name/Title:Julian C. Baker
Date:05/26/2026
Felix J. Baker
Signature:/s/ Felix J. Baker
Name/Title:Felix J. Baker
Date:05/26/2026
FBB3 LLC
Signature:/s/ Julian C. Baker
Name/Title:Manager
Date:05/26/2026