# EDGAR Filing Document

**Accession Number:** 0001551776
**File Stem:** 0000950170-25-081175
**Filing Date:** 2025-6
**Character Count:** 9592
**Document Hash:** d1099cc76e5f323b69fd4da0fd7c4415
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000950170-25-081175.hdr.sgml**: 20250603

**ACCESSION NUMBER**: 0000950170-25-081175

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20250530

**FILED AS OF DATE**: 20250603

**DATE AS OF CHANGE**: 20250603

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Vittiglio Joseph
- **CENTRAL INDEX KEY:** 0001551776

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-35966
- **FILM NUMBER:** 251021232

**MAIL ADDRESS:**
- **STREET 1:** C/O BLUEBIRD BIO, INC.
- **STREET 2:** 455 GRAND UNION BLVD
- **CITY:** SOMERVILLE
- **STATE:** MA
- **ZIP:** 02145
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** bluebird bio, Inc.
- **CENTRAL INDEX KEY:** 0001293971
- **STANDARD INDUSTRIAL CLASSIFICATION:** BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 455 GRAND UNION BOULEVARD
- **CITY:** SOMERVILLE
- **STATE:** MA
- **ZIP:** 02145
- **BUSINESS PHONE:** 339-499-9300

**MAIL ADDRESS:**
- **STREET 1:** 455 GRAND UNION BOULEVARD
- **CITY:** SOMERVILLE
- **STATE:** MA
- **ZIP:** 02145

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Genetix Pharmaceuticals Inc
- **DATE OF NAME CHANGE:** 20040616

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

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[x] 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**<sup>*</sup><br>Vittiglio Joseph<br><sub>(Last) (First) (Middle)</sub><br>C/O BLUEBIRD BIO, INC.<br>455 GRAND UNION BOULEVARD<br><sub>(Street)</sub><br>SOMERVILLE, MA 02145<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-05-30 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [ ] 10% Owner<br>[X] Officer (give title below) [ ] Other (specify below)<br>_Chief Business & Legal Officer_ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>bluebird bio, Inc. [ BLUE ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Common Stock | 2025-05-30 |  | U |  | 1143 | D | <sup>(1)(2)</sup> | 3125 | D |  |
| Common Stock | 2025-06-02 |  | D |  | 3125 | D | <sup>(3)(4)</sup> | 0 | D |  |
| Common Stock | 2025-06-02 |  | A |  | 2500 | A | <sup>(5)(6)</sup> | 2500 | D |  |
| Common Stock | 2025-06-02 |  | D |  | 2500 | D | <sup>(5)(6)</sup> | 0 | D |  |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

---

### Footnotes:

(1) In connection with the terms of an Agreement and Plan of Merger, dated as of February 21, 2025 (as amended, the "Merger Agreement"), by and among the Issuer, Beacon Parent Holdings, L.P. ("Parent") and Beacon Merger Sub, Inc., an indirect wholly owned subsidiary of Parent ("Purchaser"), Purchaser completed a tender offer for shares of the Issuer's Common Stock. Tendering stockholders were given the option to receive per share consideration of either (x) $3.00 in cash per share, subject to any applicable withholding taxes and without interest thereon, plus one contingent value right ("CVR") per share, representing the right to receive one contingent payment of $6.84, in cash, subject to any applicable withholding taxes and without interest thereon, upon achievement of the specified milestone or (y) $5.00 in cash per share, subject to any applicable withholding taxes and without interest thereon (collectively, the "Offer Price").

(2) (Continued from footnote 1) After completion of the tender offer, Purchaser merged with and into the Issuer (the "Merger"), effective as of June 2, 2025 (the "Effective Time"), with the Issuer continuing as the surviving entity and a wholly owned subsidiary of Parent.

(3) Pursuant to the terms of the Merger Agreement, immediately prior to the Effective Time, each time-based restricted stock unit award with respect to shares that is, at the time of determination, subject to vesting or forfeiture conditions and that is not a PSU Award (as defined below) (but including, for clarity, any PSU Award that is subject solely to service-based vesting conditions as of the Effective Time) ("RSU Award") that is outstanding as of immediately prior thereto, shall (a) accelerate and become fully vested, and (b) by virtue of the Merger automatically (except as otherwise provided in the Merger Agreement) and without any action on the part of the Issuer, Parent or the holder thereof, be canceled and terminated and converted into the right to receive

(4) (Continued from footnote 3) (i) an amount in cash equal to the product of the number of shares underlying such RSU Award immediately prior to the Effective Time and $3.00 in cash, subject to any applicable withholding taxes and without interest thereon plus (ii) one CVR with respect to each share subject to such RSU Award immediately prior to the Effective Time.

(5) Pursuant to the terms of the Merger Agreement, immediately prior to the Effective Time, each performance-based restricted stock unit award with respect to shares that is, at the time of determination, subject to performance-based vesting or forfeiture conditions ("PSU Award") that is outstanding and vested as of immediately prior thereto, or which shall become vested as required under the terms governing the PSU Award, shall by virtue of the Merger automatically and (except as otherwise provided in the Merger Agreement) without any action on the part of the Issuer, Parent or the holder thereof, be canceled and terminated and converted into the right to receive

(6) (Continued from footnote 5) (i) an amount in cash equal to the product of the number of shares underlying such PSU Award immediately prior to the Effective Time (assuming that the applicable performance goals have been deemed to be achieved at the greater of target and actual level of performance as determined by the Compensation Committee of the Issuer's board of directors in its discretion) and $3.00 in cash, subject to any applicable withholding taxes and without interest thereon plus (ii) one CVR with respect to each such share subject to such PSU Award immediately prior to the Effective Time.

**Signature:** /s/ Joseph Vittiglio  
**Date:** 2025-06-03

### Remarks:

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.**