[Form 4] BICYCLE THERAPEUTICS PLC Insider Trading Activity

Rhea-AI Filing Summary

Bicycle Therapeutics plc (BCYC) Chief Financial Officer Alethia Young reported sale of ordinary shares on 10/02/2025 to cover tax withholding and under a Rule 10b5-1 plan. The filing shows a sell-to-cover disposal of 217 shares at a weighted average price of $8.40 (sales ranged $8.37–$8.45) and a separate sale of 265 shares at $8.605. After the transactions the reporting person beneficially owned 44,704 ordinary shares (direct).

The report notes the 217-share sale was mandatory under the award agreement to satisfy statutory tax withholding on vested restricted stock units, while the 265-share sale followed a trading plan adopted on 04/03/2025. The filing is signed by an attorney-in-fact on 10/06/2025.

Positive

• Compliance with tax and disclosure rules—sale to cover withholding and 10b5-1 plan disclosed
• Modest transaction sizes—total of 482 shares sold, leaving substantial direct ownership of 44,704 shares

Negative

• None.

Insights

Corporate Insider / Governance Analyst

Small, compliance-driven sales; no discretionary divestiture indicated.

The transactions are routine: 217 shares were sold to satisfy tax withholding on vested restricted stock units and 265 shares executed under a Rule 10b5-1 trading plan. The sizes and prices ($8.37–$8.605) are modest relative to total holdings, and ownership remains at 44,704 shares direct.

Key dependencies are the award agreement terms and the trading plan's parameters; investors can expect similar administrative sales at vesting dates or under the plan through its effective period. Monitor any future Form 4 filings for changes in plan activity or larger discretionary trades within the next 12 months.

SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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

X

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Young Alethia

(Last) (First) (Middle)

C/O BICYCLE THERAPEUTICS PLC

BLOCKS A & B, PORTWAY BUILDING

(Street)

CAMBRIDGE X0 CB21 6GS

(City) (State) (Zip)

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 Financial Officer

3. Date of Earliest Transaction (Month/Day/Year)
10/02/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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	10/02/2025		S		217(1)	D	$8.4(2)	44,969	D
Ordinary Shares	10/02/2025		S(3)		265	D	$8.605	44,704	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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: 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

Explanation of Responses:

1. Represents the number of shares required to be sold to cover the statutory tax withholding obligations in connection with the vesting and settlement of restricted stock units. This sale is mandated by the Reporting Person's award agreement that requires the satisfaction of minimum statutory tax withholding obligations to be funded by a "sell to cover" transaction and does not represent a discretionary sale by the Reporting Person.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $8.37 to $8.45 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

3. This transaction was made pursuant to a Rule 10b5-1 trading plan adopted on April 3, 2025.

	/s/ Travis Thompson, Attorney-in-Fact	10/06/2025
	** Signature of Reporting Person	Date
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).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What did BCYC CFO Alethia Young sell on 10/02/2025?

The CFO sold 217 shares to cover statutory tax withholding at a weighted average price of $8.40 and 265 shares at $8.605 under a Rule 10b5-1 plan.

Why were 217 shares sold in the Form 4 filing?

Those 217 shares were sold to satisfy mandatory statutory tax withholding obligations arising from the vesting and settlement of restricted stock units.

Was the 265-share sale discretionary?

The 265-share sale was executed pursuant to a Rule 10b5-1 trading plan adopted on 04/03/2025, indicating preplanned execution rather than an ad-hoc discretionary sale.

How many shares does the reporting person own after these transactions?

After the reported transactions the reporting person beneficially owned 44,704 ordinary shares (direct).

What price range were the sold shares executed at?

The shares sold to cover withholding were executed at prices ranging from $8.37 to $8.45; the other sale was at $8.605.