# EDGAR Filing Document

**Accession Number:** 0001703031
**File Stem:** 0001193125-26-159765
**Filing Date:** 2026-4
**Character Count:** 13172
**Document Hash:** 9d5b9628a60afa3ad7d6a5b56d9acab1
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-159765.hdr.sgml**: 20260416

**ACCESSION NUMBER**: 0001193125-26-159765

**CONFORMED SUBMISSION TYPE**: 3

**PUBLIC DOCUMENT COUNT**: 2

**CONFORMED PERIOD OF REPORT**: 20260416

**FILED AS OF DATE**: 20260416

**DATE AS OF CHANGE**: 20260416

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Bain Capital Life Sciences Investors, LLC
- **CENTRAL INDEX KEY:** 0001703031

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43233
- **FILM NUMBER:** 26869058

**BUSINESS ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
- **BUSINESS PHONE:** 6175162878

**MAIL ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Bain Capital Life Sciences IV General Partner, LLC
- **CENTRAL INDEX KEY:** 0001996931

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43233
- **FILM NUMBER:** 26869057

**BUSINESS ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
- **BUSINESS PHONE:** 6175162000

**MAIL ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Bain Capital Life Sciences Fund IV, L.P.
- **CENTRAL INDEX KEY:** 0001996979

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43233
- **FILM NUMBER:** 26869056

**BUSINESS ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
- **BUSINESS PHONE:** 6175162000

**MAIL ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** BCLS Fund IV Investments, L.P.
- **CENTRAL INDEX KEY:** 0002015454

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43233
- **FILM NUMBER:** 26869054

**BUSINESS ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
- **BUSINESS PHONE:** 6175162000

**MAIL ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** BCLS Fund IV Investments GP, LLC
- **CENTRAL INDEX KEY:** 0002015967

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43233
- **FILM NUMBER:** 26869055

**BUSINESS ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
- **BUSINESS PHONE:** 6175162000

**MAIL ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Kailera Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0002096997
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 180 THIRD AVENUE
- **STREET 2:** 4TH FLOOR
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451
- **BUSINESS PHONE:** 508-440-9475

**MAIL ADDRESS:**
- **STREET 1:** 180 THIRD AVENUE
- **STREET 2:** 4TH FLOOR
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451

## Exhibit 99.1

**Exhibit 99.1**

**Bain Capital Life Sciences Investors, LLC**

By: <u>/s/ Adam Koppel</u>

Title: Partner

**Bain Capital Life Sciences IV General Partner, LLC**

By: Bain Capital Life Sciences Investors, LLC, its manager

By: <u>/s/ Adam Koppel</u>

Title: Partner

**Bain Capital Life Sciences Fund IV, L.P.**

By: Bain Capital Life Sciences IV General Partner, LLC, its general partner

By: Bain Capital Life Sciences Investors, LLC, its manager

By: <u>/s/ Adam Koppel</u>

Title: Partner

**BCLS Fund IV Investments GP, LLC**

By: Bain Capital Life Sciences Fund IV, L.P., its managing member

By: Bain Capital Life Sciences IV General Partner, LLC, its general partner

By: Bain Capital Life Sciences Investors, LLC, its manager

By: <u>/s/ Adam Koppel</u>

Title: Partner

**BCLS Fund IV Investments, LP**

By: BCLS Fund IV Investments GP, LLC, its general partner

By: Bain Capital Life Sciences Fund IV, L.P., its managing member

By: Bain Capital Life Sciences IV General Partner, LLC, its general partner

By: Bain Capital Life Sciences Investors, LLC, its manager

By: <u>/s/ Adam Koppel</u>

Title: Partner

------

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

## FORM 3

### INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Bain Capital Life Sciences Investors, LLC<br><sub>(Last) (First) (Middle)</sub><br>200 CLARENDON STREET<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Issuer Name and Ticker or Trading Symbol**<br>Kailera Therapeutics, Inc. [ KLRA ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2026-04-16 | **4. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director   [X] 10% Owner<br>[ ] Officer (give title below)   [ ] Other (specify below)<br>_ _ | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Bain Capital Life Sciences IV General Partner, LLC<br><sub>(Last) (First) (Middle)</sub><br>200 CLARENDON STREET<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Issuer Name and Ticker or Trading Symbol**<br>Kailera Therapeutics, Inc. [ KLRA ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2026-04-16 | **4. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director   [X] 10% Owner<br>[ ] Officer (give title below)   [ ] Other (specify below)<br>_ _ | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Bain Capital Life Sciences Fund IV, L.P.<br><sub>(Last) (First) (Middle)</sub><br>200 CLARENDON STREET<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Issuer Name and Ticker or Trading Symbol**<br>Kailera Therapeutics, Inc. [ KLRA ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2026-04-16 | **4. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director   [X] 10% Owner<br>[ ] Officer (give title below)   [ ] Other (specify below)<br>_ _ | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>BCLS Fund IV Investments GP, LLC<br><sub>(Last) (First) (Middle)</sub><br>200 CLARENDON STREET<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Issuer Name and Ticker or Trading Symbol**<br>Kailera Therapeutics, Inc. [ KLRA ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2026-04-16 | **4. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director   [X] 10% Owner<br>[ ] Officer (give title below)   [ ] Other (specify below)<br>_ _ | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>BCLS Fund IV Investments, L.P.<br><sub>(Last) (First) (Middle)</sub><br>200 CLARENDON STREET<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Issuer Name and Ticker or Trading Symbol**<br>Kailera Therapeutics, Inc. [ KLRA ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2026-04-16 | **4. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director   [X] 10% Owner<br>[ ] Officer (give title below)   [ ] Other (specify below)<br>_ _ | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities Beneficially Owned

---

|  |  |  |  |
| --- | --- | --- | --- |
| 1. Title of Security | 2. Amount of Securities Beneficially Owned | 3. Ownership Form | 4. Nature of Indirect Beneficial Ownership |

---

## Table II - Derivative Securities Beneficially Owned

---

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 3. Title and Amount of Underlying Securities | 3. Title and Amount of Underlying Securities | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| Series A-1 Preferred Stock | <sup>(1)</sup> | <sup>(1)</sup> | Common Stock | 16875000 | $0 | I | See footnotes<sup>(3)(4)</sup> |
| Series B Preferred Stock | <sup>(2)</sup> | <sup>(2)</sup> | Common Stock | 4145768 | $0 | I | See footnotes<sup>(3)(4)</sup> |

---

### Footnotes:

(1) Each share of the Issuer's Series A-1 Preferred Stock is convertible, at the option of the holder, into shares of the Issuer's Common Stock on a 1:1 basis and will automatically convert upon the closing of the Issuer's initial public offering. These securities have no expiration date.

(2) Each share of the Issuer's Series B Preferred Stock is convertible, at the option of the holder, into shares of the Issuer's Common Stock on a 1:1 basis and will automatically convert upon the closing of the Issuer's initial public offering. These securities have no expiration date.

(3) Represents shares of the Issuer's Series A-1 Preferred Stock and Series B Preferred Stock held directly by BCLS Fund IV Investments, LP ("BCLS Fund IV Investments").

(4) Bain Capital Life Sciences Investors, LLC ("BCLSI") is the manager of Bain Capital Life Sciences IV General Partner, LLC ("BCLS Fund IV GP"), which is the general partner of Bain Capital Life Sciences Fund IV, L.P. ("BCLS Fund IV"), which is the managing member of BCLS Fund IV Investments GP, LLC ("BCLS Fund IV Investments GP"), which is the general partner of BCLS Fund IV Investments. As a result, each of BCLSI, BCLS Fund IV GP, BCLS Fund IV and BCLS Fund IV Investments GP may be deemed to share voting and dispositive power with respect to the securities held by BCLS Fund IV Investments. BCLSI, BCLS Fund IV GP, BCLS Fund IV and BCLS Fund IV Investments GP each disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein.

**Signature:** See signatures included in Exhibit 99.1  
**Date:** 2026-04-16

### 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.**