# EDGAR Filing Document

**Accession Number:** 0002100174
**File Stem:** 0001193125-26-174293
**Filing Date:** 2026-4
**Character Count:** 10235
**Document Hash:** 052037e5fc9f0f5ffa0a3d2d0e370001
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-174293.hdr.sgml**: 20260423

**ACCESSION NUMBER**: 0001193125-26-174293

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D

**PUBLIC DOCUMENT COUNT**: 2

**FILED AS OF DATE**: 20260423

**DATE AS OF CHANGE**: 20260423

**SUBJECT COMPANY**: 

**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

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-95629
- **FILM NUMBER:** 26890100

**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
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** BCPE Perseus Investor, LP
- **CENTRAL INDEX KEY:** 0002100174

**ORGANIZATION NAME:**
- **EIN:** 395044097
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D

**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

### Attached PDF Documents

**Attachment 1:** `ck0000000000-ex99_b.pdf`

_No text found in this document._

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

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**Kailera Therapeutics, Inc.**

*(Name of Issuer)*

**Common Stock, $0.00001 par value per share**

*(Title of Class of Securities)*

**—**

*(CUSIP Number)*

**Bain Capital Investors, LLC**<br>200 Clarendon Street<br>Boston MA 02116<br>617-516-2000

*(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)*

**04/16/2026**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**BCPE Perseus Investor, LP** | Name of reporting person<br>**BCPE Perseus Investor, LP** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**26255581.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**26255581.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**26255581.00** | Aggregate amount beneficially owned by each reporting person<br>**26255581.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**20.27%** | Percent of class represented by amount in Row (11)<br>**20.27%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock, $0.00001 par value per share

**(b) Name of Issuer:**
Kailera Therapeutics, Inc.

**(c) Address of Issuer's Principal Executive Offices:**
180 Third Avenue, 4th Floor, Waltham, MA, 02451

**Item 4. Purpose of Transaction**

The information set forth in Item 3 of this Schedule 13D is incorporated by reference in its entirety into this Item 4.

Andrew Kaplan, a Partner of BCI, is a member of the Issuer's board of directors (the "Board").

The Reporting Person acquired the securities reported herein for investment purposes. In its capacity as a significant stockholder of the Issuer, the Reporting Person intends to take an active role in working with the Issuer's management and the Board on operational, financial and strategic initiatives. The Reporting Person reviews and intends to continue to review, on an ongoing and continuing basis, their investment in the Issuer. Depending upon the factors discussed below and subject to applicable law, the Reporting Person may from time to time acquire additional securities of the Issuer or sell or otherwise dispose of some or all of their securities of the Issuer. Any transactions that the Reporting Persons may pursue may be made at any time and from time to time without prior notice and will depend upon a variety of factors, including, without limitation, current and anticipated future trading prices of the securities of the Issuer, the financial condition, results of operations and prospects of the Issuer, general economic, financial market and industry conditions, other investment and business opportunities available to the Reporting Person, tax considerations and other factors.

**Item 5. Interest in Securities of the Issuer**

**(a)**
The information set forth in Items 2 and 3 and on the cover pages of this Schedule 13D is incorporated by reference in its entirety into this Item 5.

As of the date hereof the Reporting Person directly holds 26,255,581 shares of Common Stock, representing approximately 20.3% of the outstanding shares of Common Stock.

The percentage of the outstanding shares of Common Stock held by the Reporting Person is based on 129,537,314 shares of Common Stock issued and outstanding, as reported by the Issuer in its prospectus relating to its initial public offering (after giving effect to the full exercise of the underwriters' option to purchase additional shares), filed with the Securities and Exchange Commission pursuant to Rule 424(b) under the Securities Act of 1933, as amended, on April 17, 2026.

**(b)**
See Item 5(a) hereof.

**(c)**
See Item 3 hereof.

**Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.**

The information set forth in Item 3 of this Schedule 13D is incorporated by reference in its entirety into this Item 6.

Investor Rights Agreement.

The Reporting Person is party to the Amended and Restated Investor Rights Agreement (the "Investor Rights Agreement"), dated October 5, 2025, with the Issuer and certain other stockholders of the Issuer. The Investor Rights Agreement provides the Reporting Person with the following rights with respect to the registration of its shares of Common Stock:

Form S-1 Registration Rights.

If at any time beginning 180 days after the closing date of the Issuer's initial public offering the holders of the majority of the registrable securities request in writing that the Issuer effect a registration with respect to all or part of such registrable securities then outstanding and having an anticipated aggregate offering price that would exceed $25,000,000, net of expenses, the Issuer may be required to register their shares. The Issuer is obligated to effect at most two registrations in response to these demand registration rights.

Piggyback Registration Rights.

If, at any time after the Issuer's initial public offering, the Issuer proposes to register any shares of its Common Stock under the Securities Act of 1933, as amended, subject to certain exceptions, the holders of registrable securities will be entitled to notice of the registration and to include their shares of registrable securities in the registration.

Form S-3 Registration.

If, at any time after the Issuer becomes entitled under the Securities Act of 1933, as amended, to register its shares on a registration statement on Form S-3, the holders of at least 25% of the registrable securities request in writing that the Issuer effect a registration with respect to registrable securities at an aggregate price to the public in the offering of at least $10,000,000, the Issuer will be required to effect such registration.

Lock-Up Agreement.

In connection with the Issuer's initial public offering, the Reporting Person and Mr. Kaplan each entered into a lock-up agreement (a "Lock-Up Agreement") with the representatives of the several underwriters. Pursuant to the Lock-Up Agreement, the Reporting Person and Mr. Kaplan each agreed, subject to certain exceptions, not to sell or otherwise transfer any shares of the Issuer's Common Stock or securities convertible into or exercisable or exchangeable for, shares of Common Stock for 180 days after the date of the prospectus relating to the Issuer's initial public offering without the prior written consent of the representatives.

The foregoing summaries of the Investor Rights Agreement and Lock-Up Agreement do not purport to be complete and are qualified in their entirety by reference to the Investor Rights Agreement and Lock-Up Agreement, each of which is filed as an exhibit hereto and incorporated by reference herein.

### SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** BCPE Perseus Investor, LP

**Signature:** /s/ Andrew Kaplan

**Name/Title:** Andrew Kaplan, Partner of Bain Capital Investors, LLC

**Date:** 04/23/2026