# EDGAR Filing Document

**Accession Number:** 0001701108
**File Stem:** 0001193125-26-283033
**Filing Date:** 2026-6
**Character Count:** 11025
**Document Hash:** fa1f3618ca4ca2e325465bb14811fb8b
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-283033.hdr.sgml**: 20260625

**ACCESSION NUMBER**: 0001193125-26-283033

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 12

**CONFORMED PERIOD OF REPORT**: 20260623

**ITEM INFORMATION**: Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers

**ITEM INFORMATION**: Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year

**ITEM INFORMATION**: Submission of Matters to a Vote of Security Holders

**ITEM INFORMATION**: Financial Statements and Exhibits

**FILED AS OF DATE**: 20260625

**DATE AS OF CHANGE**: 20260625

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Spero Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001701108
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-38266
- **FILM NUMBER:** 261122935

**BUSINESS ADDRESS:**
- **STREET 1:** 675 MASSACHUSETTS AVENUE
- **STREET 2:** 14TH FLOOR
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02139
- **BUSINESS PHONE:** 857-242-1600

**MAIL ADDRESS:**
- **STREET 1:** 675 MASSACHUSETTS AVENUE
- **STREET 2:** 14TH FLOOR
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02139

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Spero Therapeutics, LLC
- **DATE OF NAME CHANGE:** 20170316

?xml version='1.0' encoding='ASCII'? 8-K

### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

### FORM 8-K

#### CURRENT REPORT

#### Pursuant to Section 13 or 15(d)

#### of The Securities Exchange Act of 1934

#### Date of Report (Date of earliest event reported): June 23, 2026

## SPERO THERAPEUTICS, INC.

#### (Exact name of registrant as specified in its charter)

---

| | | |
|:---|:---|:---|
| **Delaware** | **001-38266** | **46-4590683** |
| **(State or other jurisdiction**<br> **of incorporation)** | **(Commission**<br> **File Number)** | **(I.R.S. Employer<br>Identification No.)** |

---

---

| | |
|:---|:---|
| **675 Massachusetts Avenue, 14<sup>th</sup> Floor**<br> **Cambridge, Massachusetts** | **02139** |
| **(Address of principal executive offices)** | **(Zip Code)** |

---

#### Registrant's telephone number, including area code (857) 242-1600
Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

---

| | | |
|:---|:---|:---|
| **Title of each class** | **Trading<br>Symbol(s)** | **Name of each exchange<br>on which registered** |
| Common Stock, $0.001 par value | SPRO | The Nasdaq Global Select Market |

---

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

------

---

| | |
|:---|:---|
| **Item 5.02** | **Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers**  |

---

*Approval of the 2026 Stock Incentive Plan*

At the 2026 Annual Meeting of Stockholders (the "Annual Meeting") of Spero Therapeutics, Inc. (the "Company") held on June 23, 2026, the Company's stockholders approved the Spero Therapeutics, Inc. 2026 Stock Incentive Plan (the "2026 Plan"), which had previously been adopted by the Company's board of directors (the "Board"), subject to stockholder approval. Subject to adjustments in accordance with the 2026 Plan, up to 12,895,866 shares of common stock may be issued from time to time pursuant to the 2026 Plan.

The description of the 2026 Plan is contained on pages 49 to 59 of the Company's [proxy statement](http://www.sec.gov/Archives/edgar/data/../../../ix?doc=/Archives/edgar/data/1701108/000119312526182201/d45106ddef14a.htm#toc45106_13) for the Annual Meeting (the "Proxy Statement"), filed with the Securities and Exchange Commission (the "SEC") on April 27, 2026, is incorporated herein by reference. A complete copy of the 2026 Plan is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

---

| | |
|:---|:---|
| **Item 5.03** | **Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year.**  |

---

*Amendment to Articles of Incorporation*

At the Annual Meeting, the stockholders of the Company approved an amendment to the Company's Amended and Restated Certificate of Incorporation, to increase the total number of shares of common stock authorized for issuance thereunder from 120,000,000 shares to 240,000,000 shares. The certificate of amendment to the Company's Amended and Restated Certificate of Incorporation (the "Certificate of Amendment") was filed with the Secretary of State of the State of Delaware on June 23, 2026 and became effective upon filing.

The foregoing description is qualified in its entirety by the Certificate of Amendment, which is attached as Exhibit 3.1 and is incorporated herein by reference.

---

| | |
|:---|:---|
| **Item 5.07** | **Submission of Matters to a Vote of Stockholders**  |

---

On June 23, 2026, the Company held its Annual Meeting. Of the 57,901,493 shares of common stock issued and outstanding and eligible to vote as of the record date of April 24, 2026, a quorum of 41,061,190 shares, or approximately 70.91% of the outstanding shares, were present in person or by proxy at the Annual Meeting.

The following actions were taken at the Annual Meeting:

1. The following nominees were reelected to serve on the Company's board of directors as Class III directors until the Company's 2029 annual meeting of stockholders, based on the following votes:

---

| | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|
| **Name** | **Votes For** | **Votes For** | **Votes Withheld** | **Votes Withheld** | **Broker Non-Votes** | **Broker Non-Votes** |
|  Milind Deshpande, Ph.D. |  | 26745670 |  | 2254740 |  | 12060780 |
|  Kathleen Tregoning |  | 28259925 |  | 740485 |  | 12060780 |

---

2. The selection of PricewaterhouseCoopers LLP as the Company's independent registered public accounting firm for the fiscal year ending December 31, 2026 was ratified, based on the following votes:

---

| | | | |
|:---|:---|:---|:---|
| **Votes For** | **Votes Against** | **Votes Abstained** | **Broker Non-Votes** |
| 40866196 | 189300 | 5694 | N/A |

---

3. The advisory vote on the compensation of the Company's named executive officers, as described in the Proxy Statement, was approved, based on the following votes:

---

| | | | |
|:---|:---|:---|:---|
| **Votes For** | **Votes Against** | **Votes Abstained** | **Broker Non-Votes** |
| 27890254 | 1002982 | 107174 | 12060780 |

---

4. The amendment to the Company's Amended and Restated Certificate of Incorporation to increase the total number of shares of common stock authorized for issuance thereunder from 120,000,000 shares to 240,000,000 shares, was approved, based on the following votes:

---

| | | | |
|:---|:---|:---|:---|
| **Votes For** | **Votes Against** | **Votes Abstained** | **Broker Non-Votes** |
| 30356780 | 10558645 | 145765 | N/A |

---

5. The Spero Therapeutics, Inc. 2026 Stock Incentive Plan, was approved, based on the following votes:

---

| | | | |
|:---|:---|:---|:---|
| **Votes For** | **Votes Against** | **Votes Abstained** | **Broker Non-Votes** |
| 25379610 | 3567416 | 53384 | 12060780 |

---

------

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| | |
|:---|:---|
| **Item 9.01** | **Financial Statements and Exhibits**  |

---

(d) Exhibits

---

| | |
|:---|:---|
| **Exhibit No.** | **Description** |
| 3.1 | [Certificate of Amendment to Restated Certificate of Incorporation of Spero Therapeutics, Inc.](d86736dex31.htm) |
| 99.1 | [Spero Therapeutics, Inc. 2026 Stock Incentive Plan (incorporated by reference to Exhibit 99.1 of registrant's Registration Statement on Form S-8 (File No. 333-296972) filed with the SEC on June 23, 2026)](http://www.sec.gov/Archives/edgar/data/1701108/000119312526279429/d155753dex991.htm) |
| 104 | Cover Page Interactive Data File (embedded within the Inline XBRL document and incorporated as Exhibit 101) |

---

------

#### SIGNATURE
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

---

| | | |
|:---|:---|:---|
| Date: June 25, 2026 | **SPERO THERAPEUTICS, INC.** | **SPERO THERAPEUTICS, INC.** |
|  | By: | /s/ Esther Rajavelu |
|  |  | Esther Rajavelu |
|  |  | Chief Executive Officer and Chief Financial Officer |

---

## Exhibit 3.1

**Exhibit 3.1** 

**CERTIFICATE OF AMENDMENT** 

**TO** 

**RESTATED CERTIFICATE OF INCORPORATION** 

**OF** 

**SPERO THERAPEUTICS, INC.** 

It is hereby certified that:

---

| | |
|:---|:---|
| FIRST: | The name of the corporation is Spero Therapeutics, Inc. (the "Corporation"). |
| SECOND: | The Amended and Restated Certificate of Incorporation of the Corporation, filed on August 17, 2021 (the "Restated Certificate of Incorporation") is hereby further amended by striking out the first paragraph of the Fourth Article in its entirety and by substituting it with the following: |

---

"FOURTH. The total number of shares of all classes of stock which the Corporation shall have authority to issue is 250,000,000 shares, consisting of 240,000,000 shares of Common Stock, $0.001 par value per share (the "Common Stock") and 10,000,000 shares of Preferred Stock, $0.001 par value per share (the "Preferred Stock")."

THIRD: The amendment of the Amended and Restated Certificate of Incorporation herein certified has been duly adopted in accordance with the provisions of Section 242 of the General Corporation Law of the State of Delaware.

EXECUTED, effective as of this 23rd day of June, 2026.

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| | |
|:---|:---|
| **SPERO THERAPEUTICS, INC.** | **SPERO THERAPEUTICS, INC.** |
| By: | /s/ Esther Rajavelu |
|  | Esther Rajavelu |
|  | President and Chief Executive Officer |

---