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Spero Therapeutics (SPRO) director awarded RSUs and 20,000-share option

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

Rhea-AI Filing Summary

Spero Therapeutics director Milind Deshpande received new equity awards as part of his compensation. He was granted 10,000 restricted stock units, each representing one share of common stock upon vesting, and a stock option for 20,000 shares at an exercise price of $2.15 per share.

The RSUs vest on June 23, 2027, contingent on his continued service. The option also vests and becomes fully exercisable on June 23, 2027 under the same service condition. Following the grant, he directly holds 101,454 shares of common stock.

Positive

  • None.

Negative

  • None.
Insider Deshpande Milind
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 — 101,454 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 to director
Stock option grant 20,000 shares Option on common stock granted to director
Option exercise price $2.15/share Exercise price for 20,000-share option
Shares held after grant 101,454 shares Common stock directly owned after transaction
RSU vesting date June 23, 2027 RSUs vest if service continues through this date
Option vesting date June 23, 2027 Option becomes fully exercisable on this date
Option expiration June 23, 2036 Expiration date of the stock option
restricted stock units financial
"Consists of restricted stock units ("RSUs"). Each RSU represents the right to receive one share of common stock upon vesting."
Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.
Stock Option (right to buy) financial
"Stock Option (right to buy) with underlying security title Common Stock and 20,000.0000 underlying shares."
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.
vesting financial
"The RSUs vest on June 23, 2027, subject to the Reporting Person's continued service through the applicable vesting date."
Vesting is the process by which you earn full ownership of something, like company stock or a retirement benefit, over time. It’s like earning the right to keep a gift piece by piece the longer you stay with a company, making sure employees stay committed before they receive all the benefits.
Form 4 regulatory
"INSIDER FILING DATA (Form 4) reporting transactions in Spero Therapeutics, Inc."
Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.
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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*
Deshpande Milind

(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$0.00101,454D
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 Milind Deshpande06/25/2026
** 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 transactions did Spero Therapeutics (SPRO) report for Milind Deshpande?

Spero Therapeutics reported that director Milind Deshpande received equity awards consisting of 10,000 restricted stock units and a stock option on 20,000 shares of common stock as part of his compensation package.

How many Spero Therapeutics shares does Milind Deshpande hold after this Form 4?

After these awards, Milind Deshpande directly holds 101,454 shares of common stock. This figure reflects his position following the grant of 10,000 restricted stock units and does not include unexercised option shares.

What are the vesting terms for the new RSUs reported by Spero Therapeutics (SPRO)?

The 10,000 restricted stock units granted to Milind Deshpande vest on June 23, 2027. Each RSU converts into one share of common stock if he continues to serve through that vesting date, aligning incentives with long-term company performance.

What are the key details of the stock option granted to Milind Deshpande at Spero Therapeutics?

Milind Deshpande received a stock option for 20,000 shares of common stock with an exercise price of $2.15 per share. The option vests and becomes fully exercisable on June 23, 2027, subject to his continued service as a director.

Is the Form 4 for Spero Therapeutics (SPRO) an open-market purchase or a compensation grant?

The Form 4 shows a compensation grant, not an open-market trade. Both the 10,000 RSUs and the 20,000-share stock option are reported under code A, indicating awards or other acquisitions rather than market purchases.