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Equity awards to Spero (NASDAQ: SPRO) director Scott Jackson

Filing Impact
(Neutral)
Filing Sentiment
(Neutral)
Form Type
4

Rhea-AI Filing Summary

Spero Therapeutics director Scott Thomas Jackson reported new equity awards. He received 10,000 shares of common stock in the form of restricted stock units (RSUs), each representing one share upon vesting. These RSUs vest on June 23, 2027, conditioned on his continued service.

He was also granted stock options for 20,000 shares of common stock at an exercise price of $2.15 per share, expiring on June 23, 2036. These options vest and become exercisable in full on June 23, 2027, subject to continued board service. Following the RSU award, his direct common stock holdings total 85,000 shares. These are compensation-related grants, not open-market purchases or sales.

Positive

  • None.

Negative

  • None.
Insider Jackson Scott Thomas
Role null
Type Security Shares Price Value
Grant/Award Stock Option (right to buy) 20,000 $0.00 --
Grant/Award Common Stock 10,000 $0.00 --
Holdings After Transaction: Stock Option (right to buy) — 20,000 shares (Direct, null); Common Stock — 85,000 shares (Direct, null)
Footnotes (1)
  1. Consists of restricted stock units ("RSUs"). Each RSU represents the right to receive one share of common stock upon vesting. The RSUs vest on June 23, 2027, subject to the Reporting Person's continued service through the applicable vesting date. The shares underlying this option will vest and become exercisable in full on June 23, 2027 subject to the Reporting Person's continued service as a director through the vesting date.
RSU grant 10,000 shares Restricted stock units granted on June 23, 2026; vest June 23, 2027
Stock options granted 20,000 options Right to buy common stock granted June 23, 2026; vest June 23, 2027
Option exercise price $2.15 per share Exercise price for 20,000 stock options expiring June 23, 2036
Shares held after award 85,000 shares Total direct common stock holdings following RSU grant
Option expiration June 23, 2036 Expiration date of stock option grant for 20,000 shares
RSU vesting date June 23, 2027 Vest date for 10,000 RSUs, subject to continued service
restricted stock units ("RSUs") financial
"Consists of restricted stock units ("RSUs"). Each RSU represents the right to receive one share of common stock upon vesting."
Restricted stock units (RSUs) are a company promise to give an employee shares of stock (or cash equivalent) in the future, but only after certain conditions—usually staying with the company for a set time or hitting performance goals—are met. Investors watch RSUs because when they vest they increase the number of shares outstanding and can lead insiders to sell shares, affecting share price, company dilution and the true cost of employee pay.
Stock Option (right to buy) financial
"Stock Option (right to buy) with an exercise price of 2.1500."
exercise price financial
"conversion_or_exercise_price: "2.1500" for the stock option grant."
The exercise price is the fixed amount at which you can buy or sell an asset, like a stock, when using an options contract. It matters because it helps determine whether exercising the option will be profitable or not, depending on the current market price. Think of it as the set price you agree on today to buy or sell later.
vest financial
"The RSUs vest on June 23, 2027, subject to the Reporting Person's continued service."
A vest is the process by which an employee earns the right to receive certain benefits or ownership interests, such as stock or retirement funds, over time. It’s similar to earning a reward gradually, ensuring that the benefit becomes fully yours only after a set period or meeting specific conditions. This makes it important for investors because it determines when they can actually claim or use those benefits.
exercisable financial
"The shares underlying this option will vest and become exercisable in full on June 23, 2027."
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Learn about SEC filing dates
SEC Form 4
FORM 4UNITED 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*
Jackson Scott Thomas

(Last)(First)(Middle)
C/O SPERO THERAPEUTICS, INC.
675 MASSACHUSETTS AVENUE, 14TH FLOOR

(Street)
CAMBRIDGE MASSACHUSETTS 02139

(City)(State)(Zip)

UNITED STATES

(Country)
2. Issuer Name and Ticker or Trading Symbol
Spero Therapeutics, Inc. [ SPRO ]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
XDirector10% Owner
Officer (give title below)Other (specify below)
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
06/23/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm 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)
CodeVAmount(A) or (D)Price
Common Stock06/23/2026A10,000(1)A$0.0085,000D
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Stock Option (right to buy)$2.1506/23/2026A20,000 (2)06/23/2036Common Stock20,000$0.0020,000D
Explanation of Responses:
1. Consists of restricted stock units ("RSUs"). Each RSU represents the right to receive one share of common stock upon vesting. The RSUs vest on June 23, 2027, subject to the Reporting Person's continued service through the applicable vesting date.
2. The shares underlying this option will vest and become exercisable in full on June 23, 2027 subject to the Reporting Person's continued service as a director through the vesting date.
/s/ Maegan Deare, Attorney-in-Fact for Scott Thomas Jackson06/25/2026
** Signature of Reporting PersonDate
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)

FAQ

What insider transaction did Spero Therapeutics (SPRO) report for Scott Thomas Jackson?

Spero Therapeutics reported that director Scott Thomas Jackson received equity awards: 10,000 restricted stock units and stock options for 20,000 shares at a $2.15 exercise price, both vesting in 2027 as part of his board compensation.

How many Spero Therapeutics (SPRO) shares does Scott Thomas Jackson hold after this Form 4?

After these awards, Scott Thomas Jackson directly holds 85,000 shares of Spero Therapeutics common stock. This total reflects his position following the grant of 10,000 restricted stock units, which will settle into shares once they vest in June 2027.

What are the terms of Scott Thomas Jackson’s RSU award from Spero Therapeutics (SPRO)?

Jackson was granted 10,000 restricted stock units, each equal to one Spero Therapeutics common share upon vesting. The RSUs vest on June 23, 2027, provided he continues serving through that date, making this a time-based compensation grant.

What are the key details of Scott Thomas Jackson’s stock option grant at Spero Therapeutics (SPRO)?

He received options for 20,000 Spero Therapeutics common shares with a $2.15 exercise price. These options fully vest and become exercisable on June 23, 2027, require continued service as a director, and expire on June 23, 2036 if not exercised earlier.

Does Scott Thomas Jackson’s Form 4 for Spero Therapeutics (SPRO) show any open-market buying or selling?

The Form 4 shows only compensation-related acquisitions: 10,000 restricted stock units and 20,000 stock options. There are no open-market purchases or sales reported, and the awards were granted at no cash cost per share on the transaction date.

When will Scott Thomas Jackson’s Spero Therapeutics (SPRO) equity awards become available to him?

Both the 10,000 restricted stock units and the 20,000 stock options are scheduled to vest on June 23, 2027. Vesting and, for options, exercisability depend on Jackson continuing to serve as a director through that vesting date.