BAKER BROS. ADVISORS LP - 29 May 2026 Form 4 Insider Report for Kiniksa Pharmaceuticals International, plc (KNSA)

Reporting relationship
Director
Issuer ticker
KNSA
Reported as of
29 May 2026
Net transaction value
$0
Source evidence Original filing metadata and source links for verification. 5 source fields
SEC form
4
Accepted by SEC
02 Jun 2026, 16:30:37 UTC
Prior SEC filing
27 May 2026
Next SEC filing
05 Jun 2026
Source filing
View source filing
Reporting owner 1 detail
Reporting owner signature
By: Baker Bros. Advisors LP, Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing

Key filing fact

BAKER BROS. ADVISORS LP filed Form 4 for Kiniksa Pharmaceuticals International, plc (KNSA) on 02 Jun 2026.

Key facts

  • This page summarizes BAKER BROS. ADVISORS LP's Form 4 filing for Kiniksa Pharmaceuticals International, plc (KNSA).
  • 4 reported transactions and 12 derivative rows are listed below.
  • Accepted by SEC: 02 Jun 2026, 16:30.

Change

  • Previous filing in this sequence was filed on 27 May 2026.
  • Current net transaction value: $0.

Research use

  • This tells you what this filing adds before you inspect full transaction and derivative tables.
  • You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (6)

CIK 0001263508 Primary reporting owner

BAKER BROS. ADVISORS LP

Relationship
Director
Address
860 WASHINGTON STREET, 3RD FLOOR, NEW YORK
Signature
By: Baker Bros. Advisors LP, Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing
Signature date
02 Jun 2026
CIK 0001551139

667, L.P.

Relationship
Director
Address
860 WASHINGTON STREET, 3RD FLOOR, NEW YORK
Signature
Baker Bros. Advisors LP, Mgmt. Co. and Inv. Adviser to 667, L.P., pursuant to authority granted by Baker Biotech Capital, L.P., GP to 667, L.P. Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing
Signature date
02 Jun 2026
CIK 0001580575

Baker Bros. Advisors (GP) LLC

Relationship
Director
Address
860 WASHINGTON STREET, 3RD FLOOR, NEW YORK
Signature
By: Baker Bros. Advisors (GP) LLC, Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing
Signature date
02 Jun 2026
CIK 0001363364

Baker Brothers Life Sciences LP

Relationship
Director
Address
860 WASHINGTON STREET, 3RD FLOOR, NEW YORK
Signature
Baker Bros. Advisors LP, Mgmt. Co. and Inv. Adviser to BAKER BROTHERS LIFE SCIENCES, L.P., pursuant to authority granted by Baker Brothers Life Sciences Capital, L.P., GP to Baker Brothers Life Sciences, L.P., /s/ Name: Scott L. Lessing, Title: President
Signature date
02 Jun 2026
CIK 0001087940

BAKER FELIX

Relationship
Director
Address
860 WASHINGTON STREET, 3RD FLOOR, NEW YORK
Signature
/s/ Felix J. Baker
Signature date
02 Jun 2026
CIK 0001087939

BAKER JULIAN

Relationship
Director
Address
860 WASHINGTON STREET, 3RD FLOOR, NEW YORK
Signature
/s/ Julian C. Baker
Signature date
02 Jun 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

KNSA transaction

Class A Ordinary Shares

Award

Transaction value
Shares
+6,078
Change %
+4.4%
Price
$0.000000*
Shares after
143,277
Date
29 May 2026
Ownership
See Footnotes
Footnotes
F1, F2, F3, F4, F5, F6, F7, F8
KNSA transaction

Class A Ordinary Shares

Award

Transaction value
Shares
+6,078
Change %
+4.4%
Price
$0.000000*
Shares after
143,277
Date
29 May 2026
Ownership
See Footnotes
Footnotes
F1, F2, F3, F4, F5, F6, F7, F8
KNSA transaction

Class A Ordinary Shares

Award

Transaction value
Shares
+6,078
Change %
+4.4%
Price
$0.000000*
Shares after
143,277
Date
29 May 2026
Ownership
See Footnotes
Footnotes
F1, F2, F3, F4, F5, F6, F7, F8
KNSA transaction

Class A Ordinary Shares

Award

Transaction value
Shares
+6,078
Change %
+4.4%
Price
$0.000000*
Shares after
143,277
Date
29 May 2026
Ownership
See Footnotes
Footnotes
F1, F2, F3, F4, F5, F6, F7, F8
KNSA transaction

Class A Ordinary Shares

Award

Transaction value
Shares
+6,078
Change %
+4.4%
Price
$0.000000*
Shares after
143,277
Date
29 May 2026
Ownership
See Footnotes
Footnotes
F1, F2, F3, F4, F5, F6, F7, F8
KNSA transaction

Class A Ordinary Shares

Award

Transaction value
Shares
+6,078
Change %
+4.4%
Price
$0.000000*
Shares after
143,277
Date
29 May 2026
Ownership
See Footnotes
Footnotes
F1, F2, F3, F4, F5, F6, F7, F8
KNSA transaction

Class A Ordinary Shares

Award

Transaction value
Shares
+6,078
Change %
+0.22%
Price
$0.000000*
Shares after
2,744,894
Date
29 May 2026
Ownership
See Footnotes
Footnotes
F1, F3, F4, F5, F6, F7, F8, F9
KNSA transaction

Class A Ordinary Shares

Award

Transaction value
Shares
+6,078
Change %
+0.22%
Price
$0.000000*
Shares after
2,744,894
Date
29 May 2026
Ownership
See Footnotes
Footnotes
F1, F3, F4, F5, F6, F7, F8, F9
KNSA transaction

Class A Ordinary Shares

Award

Transaction value
Shares
+6,078
Change %
+0.22%
Price
$0.000000*
Shares after
2,744,894
Date
29 May 2026
Ownership
See Footnotes
Footnotes
F1, F3, F4, F5, F6, F7, F8, F9
KNSA transaction

Class A Ordinary Shares

Award

Transaction value
Shares
+6,078
Change %
+0.22%
Price
$0.000000*
Shares after
2,744,894
Date
29 May 2026
Ownership
See Footnotes
Footnotes
F1, F3, F4, F5, F6, F7, F8, F9
KNSA transaction

Class A Ordinary Shares

Award

Transaction value
Shares
+6,078
Change %
+0.22%
Price
$0.000000*
Shares after
2,744,894
Date
29 May 2026
Ownership
See Footnotes
Footnotes
F1, F3, F4, F5, F6, F7, F8, F9
KNSA transaction

Class A Ordinary Shares

Award

Transaction value
Shares
+6,078
Change %
+0.22%
Price
$0.000000*
Shares after
2,744,894
Date
29 May 2026
Ownership
See Footnotes
Footnotes
F1, F3, F4, F5, F6, F7, F8, F9
KNSA holding

Class A Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,840
Date
29 May 2026
Ownership
Direct
Footnotes
F10
KNSA holding

Class A Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,840
Date
29 May 2026
Ownership
Direct
Footnotes
F10
KNSA holding

Class A Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,840
Date
29 May 2026
Ownership
Direct
Footnotes
F10
KNSA holding

Class A Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,840
Date
29 May 2026
Ownership
Direct
Footnotes
F10
KNSA holding

Class A Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,840
Date
29 May 2026
Ownership
Direct
Footnotes
F10
KNSA holding

Class A Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,840
Date
29 May 2026
Ownership
Direct
Footnotes
F10
KNSA holding

Class A Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,840
Date
29 May 2026
Ownership
Direct
Footnotes
F11
KNSA holding

Class A Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,840
Date
29 May 2026
Ownership
Direct
Footnotes
F11
KNSA holding

Class A Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,840
Date
29 May 2026
Ownership
Direct
Footnotes
F11
KNSA holding

Class A Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,840
Date
29 May 2026
Ownership
Direct
Footnotes
F11
KNSA holding

Class A Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,840
Date
29 May 2026
Ownership
Direct
Footnotes
F11
KNSA holding

Class A Ordinary Shares

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,840
Date
29 May 2026
Ownership
Direct
Footnotes
F11

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

KNSA transaction Derivative

Non- Qualified Share Option (right to buy)

Award

Transaction value
Shares
+36,474
Change %
Price
$0.000000*
Shares after
36,474
Date
29 May 2026
Ownership
See Footnotes
Underlying class
Class A Ordinary Shares
Underlying amount
36,474
Exercise price
$48.38
Footnotes
F2, F3, F4, F5, F6, F7, F12
KNSA transaction Derivative

Non- Qualified Share Option (right to buy)

Award

Transaction value
Shares
+36,474
Change %
Price
$0.000000*
Shares after
36,474
Date
29 May 2026
Ownership
See Footnotes
Underlying class
Class A Ordinary Shares
Underlying amount
36,474
Exercise price
$48.38
Footnotes
F2, F3, F4, F5, F6, F7, F12
KNSA transaction Derivative

Non- Qualified Share Option (right to buy)

Award

Transaction value
Shares
+36,474
Change %
Price
$0.000000*
Shares after
36,474
Date
29 May 2026
Ownership
See Footnotes
Underlying class
Class A Ordinary Shares
Underlying amount
36,474
Exercise price
$48.38
Footnotes
F2, F3, F4, F5, F6, F7, F12
KNSA transaction Derivative

Non- Qualified Share Option (right to buy)

Award

Transaction value
Shares
+36,474
Change %
Price
$0.000000*
Shares after
36,474
Date
29 May 2026
Ownership
See Footnotes
Underlying class
Class A Ordinary Shares
Underlying amount
36,474
Exercise price
$48.38
Footnotes
F2, F3, F4, F5, F6, F7, F12
KNSA transaction Derivative

Non- Qualified Share Option (right to buy)

Award

Transaction value
Shares
+36,474
Change %
Price
$0.000000*
Shares after
36,474
Date
29 May 2026
Ownership
See Footnotes
Underlying class
Class A Ordinary Shares
Underlying amount
36,474
Exercise price
$48.38
Footnotes
F2, F3, F4, F5, F6, F7, F12
KNSA transaction Derivative

Non- Qualified Share Option (right to buy)

Award

Transaction value
Shares
+36,474
Change %
Price
$0.000000*
Shares after
36,474
Date
29 May 2026
Ownership
See Footnotes
Underlying class
Class A Ordinary Shares
Underlying amount
36,474
Exercise price
$48.38
Footnotes
F2, F3, F4, F5, F6, F7, F12
KNSA transaction Derivative

Non- Qualified Share Option (right to buy)

Award

Transaction value
Shares
+36,474
Change %
Price
$0.000000*
Shares after
36,474
Date
29 May 2026
Ownership
See Footnotes
Underlying class
Class A Ordinary Shares
Underlying amount
36,474
Exercise price
$48.38
Footnotes
F3, F4, F5, F6, F7, F9, F12
KNSA transaction Derivative

Non- Qualified Share Option (right to buy)

Award

Transaction value
Shares
+36,474
Change %
Price
$0.000000*
Shares after
36,474
Date
29 May 2026
Ownership
See Footnotes
Underlying class
Class A Ordinary Shares
Underlying amount
36,474
Exercise price
$48.38
Footnotes
F3, F4, F5, F6, F7, F9, F12
KNSA transaction Derivative

Non- Qualified Share Option (right to buy)

Award

Transaction value
Shares
+36,474
Change %
Price
$0.000000*
Shares after
36,474
Date
29 May 2026
Ownership
See Footnotes
Underlying class
Class A Ordinary Shares
Underlying amount
36,474
Exercise price
$48.38
Footnotes
F3, F4, F5, F6, F7, F9, F12
KNSA transaction Derivative

Non- Qualified Share Option (right to buy)

Award

Transaction value
Shares
+36,474
Change %
Price
$0.000000*
Shares after
36,474
Date
29 May 2026
Ownership
See Footnotes
Underlying class
Class A Ordinary Shares
Underlying amount
36,474
Exercise price
$48.38
Footnotes
F3, F4, F5, F6, F7, F9, F12
KNSA transaction Derivative

Non- Qualified Share Option (right to buy)

Award

Transaction value
Shares
+36,474
Change %
Price
$0.000000*
Shares after
36,474
Date
29 May 2026
Ownership
See Footnotes
Underlying class
Class A Ordinary Shares
Underlying amount
36,474
Exercise price
$48.38
Footnotes
F3, F4, F5, F6, F7, F9, F12
KNSA transaction Derivative

Non- Qualified Share Option (right to buy)

Award

Transaction value
Shares
+36,474
Change %
Price
$0.000000*
Shares after
36,474
Date
29 May 2026
Ownership
See Footnotes
Underlying class
Class A Ordinary Shares
Underlying amount
36,474
Exercise price
$48.38
Footnotes
F3, F4, F5, F6, F7, F9, F12
* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 12 footnotes

Footnote F1

Includes 2,026 restricted share units (each an "RSU") payable solely in Class A ordinary shares ("Class A Ordinary Shares") granted by Kiniksa Pharmaceuticals International, plc. (the "Issuer") to each of Felix J. Baker, a managing member of Baker Bros. Advisors (GP) LLC (the "Adviser GP"), and Dr. Stephen R. Biggar and M. Cantey Boyd, employees of Baker Bros. Advisors LP (the "Adviser"), on May 29, 2026, pursuant to the Issuer's 2018 Incentive Award Plan, as amended (the "Incentive Award Plan"). The RSUs fully vest on the earlier of May 29, 2027 or the date of the next annual meeting of shareholders of the Issuer, subject to the applicable director's continuous service on the board of directors of the Issuer (the "Board") through the vesting date. Felix J. Baker, Dr. Biggar and M. Cantey Boyd serve on the Board as representatives of 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds") and their affiliates and control persons.

Footnote F2

After giving effect to the transactions reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in Class A Ordinary Shares reported in column 5 of Table I and the Share Options (as defined below) reported in column 9 of Table II held directly by or held for the benefit of 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

Footnote F3

Pursuant to the policies of the Adviser, Felix J. Baker, Dr. Biggar and M. Cantey Boyd do not have a right to any of the Issuer's securities issued as compensation for their service on the Board and the Funds are entitled to an indirect proportionate pecuniary interest in such securities. The Funds each own an indirect proportionate pecuniary interest in the non-qualified share options exercisable solely into Class A Ordinary Shares ("Share Options") and RSUs. Solely as a result of their ownership interest in (i) the general partners of the Funds and (ii) the Funds, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Share Options, RSUs and any Class A Ordinary Shares acquired upon the exercise of Share Options or vesting of RSUs (i.e. no direct pecuniary interest) issued as compensation for such Board Service.

Footnote F4

The Adviser serves as the investment adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held directly by the Funds or for the benefit of the Funds. The Adviser GP is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held directly by the Funds or for the benefit of the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held directly by the Funds or for the benefit of the Funds.

Footnote F5

Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by or held for the benefit of the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

Footnote F6

Pursuant the policies of the Adviser, the Adviser has voting and dispositive power over the Share Options, RSUs and any Class A Ordinary Shares received as a result of the exercise of Share Options or vesting of RSUs.

Footnote F7

The acquisitions of the RSUs and Share Options reported on this form represent grants to each of Felix J. Baker, Dr. Biggar and M. Cantey Boyd of 2,026 RSUs on Table I and 12,158 Share Options on Table II. These grants, totaling 6,078 RSUs and 36,474 Share Options for Felix J. Baker, Dr. Biggar and M. Cantey Boyd in the aggregate, are reported for each of the Funds as each has an indirect pecuniary interest in such securities.

Footnote F8

Includes beneficial ownership of 15,345 Class A Ordinary Shares received from vested RSUs each previously granted to Felix J. Baker and Dr. Biggar and 7,529 Class A Ordinary Shares received from vested RSUs previously granted to M. Cantey Boyd, in their capacity as directors of the Issuer.

Footnote F9

After giving effect to the transactions reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital, L.P. and (ii) Life Sciences, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in Class A Ordinary Shares reported in column 5 of Table I and the Share Options reported in column 9 of Table II held directly by or held for the benefit of Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

Footnote F10

Class A Ordinary Shares held directly by Felix J. Baker.

Footnote F11

Class A Ordinary Shares held directly by Julian C. Baker.

Footnote F12

Includes 12,158 Share Options granted by the Issuer to each of Felix J. Baker, Dr. Biggar and M. Cantey Boyd on May 29, 2026, pursuant to the Incentive Award Plan. The Share Options have a strike price of $48.38 and vest in 12 equal monthly installments beginning on June 29, 2026 with the final installment vesting on the earlier of May 29, 2027 or the date of the next annual meeting of shareholders of the Issuer, subject to the applicable director's continuous service on the Board through the vesting date. The Share Options expire 10 years from the date of grant.

SEC remarks

Felix J. Baker, a managing member of Baker Bros. Advisors (GP) LLC, and Dr. Biggar and M. Cantey Boyd, employees of Baker Bros. Advisors LP, are directors of Kiniksa Pharmaceuticals International, plc. (the "Issuer"). By virtue of their representation on the board of directors of the Issuer, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, the reporting persons other than Felix J. Baker are deemed directors by deputization of the Issuer.

We use cookies and similar technologies to provide certain features, enhance the user experience and, if you allow them, measure engagement and deliver advertising. Analytics and marketing storage stay off until you grant consent. By clicking on "Agree and continue", you declare your consent to the use of the selected optional cookies. Manage preferences to update or revoke optional consent for future visits. For more information, see our Privacy Policy .