Rallybio director Mackay exercises options for 33,224 shares

Q: How many RLYB shares did Martin Mackay receive from option exercises?

Martin Mackay acquired 33,224 Common Stock shares on November 4, 2026, through three option exercises. The lots were 11,607, 3,562 and 18,055 shares.

Q: What were the exercise prices for Martin Mackay's RLYB options?

The exercise prices were $7.60 per share for 11,607 shares, $2.38 for 3,562 shares and $4.45 for 18,055 shares. The options expire January 2, 2035, May 13, 2035 and February 18, 2036, respectively.

Q: What were the vesting terms for Martin Mackay's RLYB options?

The 11,607-share option vested in 12 equal installments, each on the last day of a month in 2025. The 3,562-share option vested on the earlier of May 13, 2026, or the date of Rallybio's 2026 Annual Meeting of Stockholders. The 18,055-share option's vesting was accelerated in full, and it became fully vested and exercisable on October 26, 2026.

Two of the exercised options were issued under Rallybio's 2021 Equity Incentive Plan in lieu of $65,000 in retainer fees each.

Available on EDGAR 11/05/2026 - 05:04 PM EST Accepted by SEC EDGAR 11/05/2026 - 05:04 PM EST

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Rhea-AI Filing Summary

Rallybio Corp director Martin Mackay exercised three stock options on November 4, 2026, acquiring 33,224 Common Stock shares in total. The exercises covered 11,607 shares at $7.60 per share, 3,562 at $2.38 and 18,055 at $4.45. The options expire January 2, 2035, May 13, 2035 and February 18, 2036, respectively. Two options were issued in lieu of retainer fees of $65,000 each.

Insider Trade Summary

33,224 shares exercised/converted

Exercise 6 txns

Insider MACKAY MARTIN

Role Director

Type	Security	Shares	Price	Value
Exercise	Option (Right to Buy) ^{F2, F1}	11,607	$5.60	$65K
Exercise	Option (Right to Buy) ^F3	3,562	$0.00	$0.00
Exercise	Option (Right to Buy) ^{F5, F4}	18,055	$3.60	$65K
Exercise	Common Stock	11,607	$7.60	$88K
Exercise	Common Stock	3,562	$2.38	$8K
Exercise	Common Stock	18,055	$4.45	$80K

Holdings After Transaction: Option (Right to Buy) — 0 contracts (Direct); Common Stock — 125,032 shares (Direct)

Footnotes (5)

F1. The option vests as to the underlying shares of Common Stock in 12 equal installments, each on the last day of each month of calendar year 2025.
F2. This option was issued to the reporting person pursuant to the Company's 2021 Equity Incentive Plan in lieu of retainer fees of $65,000.
F3. The option was granted under the Company's 2021 Equity Incentive Plan. The option vests on the earlier of May 13, 2026 or the date of the Company's 2026 Annual Meeting of Stockholders.
F4. The option is granted under the Company's 2021 Equity Incentive Plan. On October 26, 2026, the vesting of the option was accelerated in full, and the option became fully vested and exercisable as of that date.
F5. This option was issued to the reporting person pursuant to the Company's 2021 Equity Incentive Plan in lieu of retainer fees of $65,000.

Key Figures

Common Stock shares acquired through option exercises: 33,224 shares Option exercise: 11,607 shares at $7.60 per share Option exercise: 3,562 shares at $2.38 per share +1 more

4 metrics

Common Stock shares acquired through option exercises 33,224 shares November 4, 2026

Option exercise 11,607 shares at $7.60 per share November 4, 2026

Option exercise 3,562 shares at $2.38 per share November 4, 2026

Option exercise 18,055 shares at $4.45 per share November 4, 2026

Key Terms

2021 Equity Incentive Plan, underlying shares of Common Stock, 12 equal installments, fully vested and exercisable

4 terms

2021 Equity Incentive Plan financial

"pursuant to the Company's 2021 Equity Incentive Plan"

underlying shares of Common Stock technical

"vests as to the underlying shares of Common Stock"

12 equal installments technical

"vests as to the underlying shares of Common Stock in 12 equal installments"

fully vested and exercisable technical

"became fully vested and exercisable as of that date"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many RLYB shares did Martin Mackay receive from option exercises?

Martin Mackay acquired 33,224 Common Stock shares on November 4, 2026, through three option exercises. The lots were 11,607, 3,562 and 18,055 shares.

What were the exercise prices for Martin Mackay's RLYB options?

The exercise prices were $7.60 per share for 11,607 shares, $2.38 for 3,562 shares and $4.45 for 18,055 shares. The options expire January 2, 2035, May 13, 2035 and February 18, 2036, respectively.

What were the vesting terms for Martin Mackay's RLYB options?

The 11,607-share option vested in 12 equal installments, each on the last day of a month in 2025. The 3,562-share option vested on the earlier of May 13, 2026, or the date of Rallybio's 2026 Annual Meeting of Stockholders. The 18,055-share option's vesting was accelerated in full, and it became fully vested and exercisable on October 26, 2026.

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

Form 4 Insider Transactions: What Each Field Means →

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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^*

MACKAY MARTIN

(Last)

(First)

(Middle)

C/O RALLYBIO CORPORATION

PO BOX 325

(Street)

EAST BERLIN

CONNECTICUT

06023

(City)

(State)

(Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Rallybio Corp [ RLYB ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
	Officer (give title below)	Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
11/04/2026

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

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

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

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	11/04/2026		M		11,607	A	$7.6	103,415	D
Common Stock	11/04/2026		M		3,562	A	$2.38	106,977	D
Common Stock	11/04/2026		M		18,055	A	$4.45	125,032	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Option (Right to Buy)	$7.6	11/04/2026		M			11,607	⁽¹⁾	01/02/2035	Common Stock	11,607	$5.6⁽²⁾	0	D
Option (Right to Buy)	$2.38	11/04/2026		M			3,562	⁽³⁾	05/13/2035	Common Stock	3,562	$0	0	D
Option (Right to Buy)	$4.45	11/04/2026		M			18,055	⁽⁴⁾	02/18/2036	Common Stock	18,055	$3.6⁽⁵⁾	0	D

Explanation of Responses:

1. The option vests as to the underlying shares of Common Stock in 12 equal installments, each on the last day of each month of calendar year 2025.

2. This option was issued to the reporting person pursuant to the Company's 2021 Equity Incentive Plan in lieu of retainer fees of $65,000.

3. The option was granted under the Company's 2021 Equity Incentive Plan. The option vests on the earlier of May 13, 2026 or the date of the Company's 2026 Annual Meeting of Stockholders.

4. The option is granted under the Company's 2021 Equity Incentive Plan. On October 26, 2026, the vesting of the option was accelerated in full, and the option became fully vested and exercisable as of that date.

5. This option was issued to the reporting person pursuant to the Company's 2021 Equity Incentive Plan in lieu of retainer fees of $65,000.

	By: /s/ Jonathan Lieber, Attorney-in-Fact	11/05/2026
	** 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.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR