Sec Form 3 Filing - Perry Jennifer Scott @ BICYCLE THERAPEUTICS PLC - 2026-03-17

FORM 3 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Perry Jennifer Scott 2. Issuer Name and Ticker or Trading Symbol BICYCLE THERAPEUTICS PLC [ BCYC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Operating Officer (Last) (First) (Middle) C/O BICYCLE THERAPEUTICS PLC, BLOCKS A & B, PORTWAY BUILDING 3. Date of Earliest Transaction (MM/DD/YY) 03/17/2026 (Street) CAMBRIDGECB21 6GS 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Ordinary Shares ( 1 ) 93,872 ( 2 ) D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Employee Stock Option (right to buy) $ 26.45 ( 3 ) 09/01/2032 Ordinary Shares 20,000 D Employee Stock Option (right to buy) $ 29.6 ( 4 ) 01/03/2033 Ordinary Shares 3,576 D Employee Stock Option (right to buy) $ 20.02 ( 5 ) 03/13/2033 Ordinary Shares 30,000 D Employee Stock Option (right to buy) $ 18.08 ( 6 ) 01/02/2034 Ordinary Shares 31,000 D Employee Stock Option (right to buy) $ 22.6 ( 7 ) 07/16/2034 Ordinary Shares 58,000 D Employee Stock Option (right to buy) $ 14 ( 8 ) 01/02/2035 Ordinary Shares 87,000 D Employee Stock Option (right to buy) $ 7.08 ( 9 ) 01/02/2036 Ordinary Shares 100,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Perry Jennifer Scott C/O BICYCLE THERAPEUTICS PLC BLOCKS A & B, PORTWAY BUILDING CAMBRIDGECB21 6GS Chief Operating Officer Signatures /s/ Travis Thompson, Attorney-in-Fact 03/25/2026 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Ordinary Shares may be represented by American Depositary Shares, each of which represents one ordinary share. ( 2 )Includes 84,697 restricted share units ("RSUs"). 447 RSUs vest in four equal quarterly installments commencing on April 3, 2026; 8,000 RSUs vest in eight equal quarterly installments commencing on April 2, 2026; 26,250 RSUs vest in twelve equal quarterly installments commencing on April 2, 2026; and 50,000 RSUs vest one-fourth (1/4) on January 2, 2027 and the remaining RSUs vest in twelve equal quarterly installments thereafter. ( 3 )This option vested with respect to one-fourth (1/4) of the total number of shares underlying the option on August 24, 2023 and the remaining shares vested or vest in 36 equal monthly installments thereafter. ( 4 )This option vested with respect to one-fourth (1/4) of the total number of shares underlying the option on January 3, 2024 and the remaining shares vested or vest in 36 equal monthly installments thereafter. ( 5 )This option vested with respect to one-fourth (1/4) of the total number of shares underlying the option on March 13, 2024 and the remaining shares vested or vest in 36 equal monthly installments thereafter. ( 6 )This option vested with respect to one-fourth (1/4) of the total number of shares underlying the option on January 2, 2025 and the remaining shares vested or vest in 36 equal monthly installments thereafter. ( 7 )This option vested with respect to one-fourth (1/4) of the total number of shares underlying the option on July 16, 2025 and the remaining shares vested or vest in 36 equal monthly installments thereafter. ( 8 )This option vested with respect to one-fourth (1/4) of the total number of shares underlying the option on January 2, 2026 and the remaining shares vested or vest in 36 equal monthly installments thereafter. ( 9 )This option vests with respect to one-fourth (1/4) of the total number of shares underlying the option on January 2, 2027 and the remaining shares vest in 36 equal monthly installments thereafter.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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