# EDGAR Filing Document

**Accession Number:** 0002022626
**File Stem:** 0001193125-26-265800
**Filing Date:** 2026-6
**Character Count:** 6231
**Document Hash:** 551163b87459f81c9c74aba05089c08c
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-265800.hdr.sgml**: 20260610

**ACCESSION NUMBER**: 0001193125-26-265800

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 9

**CONFORMED PERIOD OF REPORT**: 20260609

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

**FILED AS OF DATE**: 20260610

**DATE AS OF CHANGE**: 20260610

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Upstream Bio, Inc.
- **CENTRAL INDEX KEY:** 0002022626
- **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:** 001-42366
- **FILM NUMBER:** 261079637

**BUSINESS ADDRESS:**
- **STREET 1:** 890 WINTER STREET, SUITE 200
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451
- **BUSINESS PHONE:** 781-208-2466

**MAIL ADDRESS:**
- **STREET 1:** 890 WINTER STREET, SUITE 200
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451

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

**UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549**

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## FORM 8-K

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**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 09, 2026<br>

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UPSTREAM BIO, INC.

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

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| | | |
|:---|:---|:---|
| Delaware | 001-42366 | 38-4187694 |
| **(State or other jurisdiction<br>of incorporation)** | **(Commission file number)** | **(IRS employer<br>identification no.)** |
| 890 Winter Street<br>Suite 200 |  |  |
| Waltham**,** Massachusetts |  | 02451 |
| **(Address of principal executive offices)** |  | **(Zip code)** |

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**Registrant's telephone number, including area code:** (781) 208-2466<br>

Not Applicable

**(Former name or former address, if changed since last report)**

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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:**

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

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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. ☐

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## Item 5.07 Submission of Matters to a Vote of Security Holders.
Upstream Bio, Inc. (the "Company") held its 2026 Annual Meeting of Stockholders (the "Annual Meeting") on June 9, 2026. As of the close of business on April 13, 2026, the record date for the Annual Meeting, there were 54,419,986 shares of the Company's common stock outstanding and entitled to vote at the Annual Meeting, of which 48,100,767 shares were present virtually or represented by proxy at the Annual Meeting, constituting a quorum for the transaction of business at the Annual Meeting. The Company's stockholders voted on the following matters, which are described in detail in the Company's Definitive Proxy Statement filed with the U.S. Securities and Exchange Commission on April 16, 2026: (i) to elect each of H. Edward Fleming, Jr., M.D. and Liam Ratcliffe, M.B.Ch.B., Ph.D., M.B.A. as Class II directors of the Company, each to serve until the Company's 2029 annual meeting of stockholders and until his respective successor has been duly elected and qualified, or until his earlier death, resignation or removal ("Proposal 1"), and (ii) to ratify the appointment of PricewaterhouseCoopers LLP ("PwC") as the Company's independent registered public accounting firm for the fiscal year ending December 31, 2026 ("Proposal 2"). The voting results reported below are final.

<u>Proposal 1 - Election of Class II Director Nominees</u>

The Company's stockholders approved the Class II director nominees recommended for election in Proposal 1 at the Annual Meeting. The results of Proposal 1 were as follows:

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| | | | |
|:---|:---|:---|:---|
| **Class II Director Nominee** | **For** | **Withheld** | **Broker<br>Non-Votes** |
| H. Edward Fleming, Jr., M.D. | 40,715,035 | 3,367,258 | 4,018,474 |
| Liam Ratcliffe, M.B.Ch.B., Ph.D., M.B.A. | 43,812,021 | 270,272 | 4,018,474 |

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<u>Proposal 2 - Ratification of Appointment of the Company's Independent Registered Public Accounting Firm</u>

The Company's stockholders ratified the appointment of PwC as the Company's independent registered public accounting firm for the fiscal year ending December 31, 2026. The results of Proposal 2 were as follows:

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| | | |
|:---|:---|:---|
| **For** | **Against** | **Abstain** |
| 47,951,313 | 143,251 | 6,203 |

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No other matters were submitted to or voted on by the Company's stockholders at the Annual Meeting.

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**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.

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| | | | |
|:---|:---|:---|:---|
|  |  |  | Upstream Bio, Inc. |
| Date: | June 10, 2026 | By:  | /s/ E. Rand Sutherland |
|  |  |  | E. Rand Sutherland, M.D.<br>Chief Executive Officer |

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