[Form 4] BICYCLE THERAPEUTICS PLC Insider Trading Activity

Rhea-AI Filing Summary

Reporting person: Alistair Milnes, Chief Operating Officer of Bicycle Therapeutics PLC (BCYC), reported two required "sell to cover" stock sales tied to the vesting and settlement of restricted stock units. On 10/02/2025 he sold 1,147 ordinary shares at a weighted average price of $8.40, and on 10/03/2025 he sold 978 shares at a weighted average price of $8.41, totaling 2,125 shares sold to satisfy statutory tax withholding. After these transactions he beneficially owned 93,377 ordinary shares. The filing notes the sales were mandated by the award agreement and not discretionary; prices reported are weighted averages across multiple trades.

Positive

• Sale was non-discretionary and tied to RSU tax withholding, reducing signal of insider loss of confidence
• Reporting person retains substantial ownership with 93,377 shares remaining after the transactions

Negative

• Insider sold 2,125 shares, which could be perceived negatively by some market participants despite the stated reason
• Weighted-average sale prices indicate multiple trades over a range, which can complicate immediate price interpretation

Insights

Corporate Governance Analyst

TL;DR: Insider sales were administrative, not discretionary, tied to RSU tax withholding.

The sold shares total 2,125 and were executed solely to satisfy statutory tax withholding obligations from vested restricted stock units rather than an open-market decision to reduce ownership. This distinction is important because mandatory "sell to cover" transactions generally do not signal a change in insider conviction.

Risks include the potential for market perception that insiders are selling; monitor trading volumes and any subsequent discretionary sales over the next 30-90 days for a clearer signal about insider sentiment.

Executive Compensation Specialist

TL;DR: The transaction reflects routine RSU settlement mechanics under the award agreement.

The footnote clarifies the award agreement requires minimum statutory tax withholding to be funded by a sell-to-cover mechanism. Such provisions are common in equity compensation plans and do not change the economic alignment provided by the remaining equity holdings.

Concrete item to watch: any future filings showing additional vesting events or discretionary sales, and changes to the reporting person's total beneficial ownership from 93,377 shares will indicate whether compensation dilution or retention patterns shift over the next year.

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).

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^*

Milnes Alistair

(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 OPERATING 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		1,147(1)	D	$8.4(2)	94,355	D
Ordinary Shares	10/03/2025		S		978(1)	D	$8.41(3)	93,377	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 $8.31 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 ranges set forth in footnotes (2) and (3).

3. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $8.40 to $8.50 inclusive.

	/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 insider Alistair Milnes sell and why?

He sold a total of 2,125 ordinary shares in two transactions on 10/02/2025 and 10/03/2025; the sales were mandated "sell to cover" transactions to satisfy statutory tax withholding on vested restricted stock units.

How much did the BCYC shares sell for on Form 4?

The filing reports weighted average prices of $8.40 (first sale) and $8.41 (second sale); trade price ranges were $8.31-$8.45 and $8.40-$8.50, respectively.

How many BCYC shares does Alistair Milnes own after the transactions?

After the reported transactions he beneficially owned 93,377 ordinary shares.

Were these sales discretionary insider trades?

No; the filing explicitly states the sales were required by the award agreement to cover minimum statutory tax withholding and were not discretionary sales by the reporting person.

Where can I find more detail on the exact prices for each trade?

The filing notes the reported prices are weighted averages and states the reporting person will provide specific per-trade details to the issuer, shareholders, or SEC staff upon request.