Bain Capital entities (NASDAQ: KLRA) boost Kailera stake with IPO conversion and share purchase

Rhea-AI Filing Summary

Bain Capital–affiliated entities significantly increased their stake in Kailera Therapeutics, Inc. through BCPE Perseus Investor, LP. On April 20, 2026, BCPE Perseus reported an open-market purchase of 8,398,438 shares of Kailera common stock at $16.00 per share, bringing one reported indirect holding line to 26,255,581 shares.

On the same date, each share of Kailera’s Series B Preferred Stock automatically converted into common stock on a 1:1 basis upon the closing of Kailera’s initial public offering, resulting in 17,857,143 newly issued common shares and reducing the reported Series B Preferred Stock position to zero. All securities are held directly by BCPE Perseus, while Bain Capital Investors, LLC and related Bain Capital funds may be deemed to share voting and dispositive power but disclaim beneficial ownership except for their pecuniary interests.

Insights

Equity ownership & insider-transactions analyst

Bain Capital entities, via BCPE Perseus, added common shares through a large IPO-linked conversion plus an open-market buy.

The filing shows BCPE Perseus Investor, LP acquiring Kailera Therapeutics common stock in two ways on April 20, 2026. First, 8,398,438 shares were bought in an open-market purchase at $16.00 per share. Second, 17,857,143 shares of Series B Preferred Stock automatically converted into an equal number of common shares upon the closing of Kailera’s initial public offering.

After these transactions, one reported indirect common stock holding stands at 26,255,581 shares, and the converted block shows 17,857,143 common shares following the transaction. The derivative position in Series B Preferred Stock fell to zero. Although Bain Capital Investors, LLC and related entities may be deemed to share voting and dispositive power, the filing notes they each disclaim beneficial ownership except to the extent of their pecuniary interest.

Insider Trade Summary

Net Buyer: 8,398,438 shares ($134,375,008)

Net Buy 3 txns

Insider BAIN CAPITAL INVESTORS LLC, Bain Capital XIV General Partner, LLC, Bain Capital Fund XIV, L.P., BCPE Perseus Investor GP, LLC, BCPE Perseus Investor, LP

Role null | null | null | null | null

Bought 8,398,438 shs ($134.38M)

Type	Security	Shares	Price	Value
Conversion	Series B Preferred Stock	17,857,143	$0.00	--
Conversion	Common Stock	17,857,143	$0.00	--
Purchase	Common Stock	8,398,438	$16.00	$134.38M

Holdings After Transaction: Series B Preferred Stock — 0 shares (Indirect, See footnotes); Common Stock — 17,857,143 shares (Indirect, See footnotes)

Footnotes (1)

1. Each share of the Issuer's Series B Preferred Stock automatically converted into shares of the Issuer's Common Stock on a 1:1 basis upon the closing of the Issuer's initial public offering. These securities had no expiration date. Represents securities held directly by BCPE Perseus Investor, LP ("BCPE Perseus"). Bain Capital Investors, LLC ("BCI") is the manager of Bain Capital XIV General Partner, LLC ("BCPE Fund XIV GP"), which is the general partner of Bain Capital Fund XIV, L.P. ("BCPE Fund XIV"), which is the managing member of BCPE Perseus Investor GP, LLC ("BCPE Perseus GP"), which is the general partner of BCPE Perseus. As a result, each of BCI, BCPE Fund XIV GP, BCPE Fund XIV and BCPE Perseus GP may be deemed to share voting and dispositive power with respect to the securities held by BCPE Perseus. BCI, BCPE Fund XIV GP, BCPE Fund XIV and BCPE Perseus GP each disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein.

Key Figures

Open-market purchase: 8,398,438 shares at $16.00 Common shares after purchase: 26,255,581 shares Preferred-to-common conversion: 17,857,143 shares +2 more

5 metrics

Open-market purchase 8,398,438 shares at $16.00 Common Stock bought on April 20, 2026

Common shares after purchase 26,255,581 shares Indirect holding line following open-market buy

Preferred-to-common conversion 17,857,143 shares Series B Preferred converting 1:1 into Common Stock

Series B Preferred remaining 0 shares Series B Preferred Stock after conversion

Net buy shares 8,398,438 shares Net buy/sell shares in transaction summary

Key Terms

open-market purchase, Conversion of derivative security, Series B Preferred Stock, initial public offering, +1 more

5 terms

open-market purchase financial

"transaction_action: "open-market purchase""

An open-market purchase is when an investor or a company buys shares on a public stock exchange at the going market price, rather than through a private deal. It matters to investors because these purchases change how many shares are available, can push the stock price up or signal confidence from large buyers, and often affect per-share metrics like earnings—think of it like someone buying lots of apples off a grocery shelf, reducing supply and potentially raising the price.

Conversion of derivative security financial

"transaction_code_description: "Conversion of derivative security""

Series B Preferred Stock financial

"security_title: "Series B Preferred Stock""

Series B preferred stock is a type of ownership share issued by a company that offers certain advantages over common stock, such as priority in receiving dividends or assets if the company is sold or liquidated. It is typically issued after an initial round of funding, making it a way for investors to support a company's growth while gaining some protections and benefits. This stock matters to investors because it often provides a more secure investment position with potential for future growth.

initial public offering financial

"upon the closing of the Issuer's initial public offering"

An initial public offering (IPO) is when a private company first sells its shares to the public and becomes a stock-listed company. It matters because it allows the company to raise money from a wide range of investors, helping it grow, while giving early shareholders a way to sell some of their ownership.

pecuniary interest financial

"disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein"

Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

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

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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^*

BAIN CAPITAL INVESTORS LLC

(Last) (First) (Middle)

200 CLARENDON STREET

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Kailera Therapeutics, Inc. [ KLRA ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/20/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

	Form filed by One Reporting Person
X	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	04/20/2026		C		17,857,143	A	(1)	17,857,143	I	See footnotes(2)(3)
Common Stock	04/20/2026		P		8,398,438	A	$16	26,255,581	I	See footnotes(2)(3)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series B Preferred Stock	(1)	04/20/2026		C			17,857,143	(1)	(1)	Common Stock	17,857,143	$0	0	I	See footnotes(2)(3)

1. Name and Address of Reporting Person^*

BAIN CAPITAL INVESTORS LLC

(Last) (First) (Middle)

200 CLARENDON STREET

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Bain Capital XIV General Partner, LLC

(Last) (First) (Middle)

200 CLARENDON STREET

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Bain Capital Fund XIV, L.P.

(Last) (First) (Middle)

200 CLARENDON STREET

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

BCPE Perseus Investor GP, LLC

(Last) (First) (Middle)

200 CLARENDON STREET

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

BCPE Perseus Investor, LP

(Last) (First) (Middle)

200 CLARENDON STREET

(Street)

BOSTON MASSACHUSETTS 02116

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

Explanation of Responses:

1. Each share of the Issuer's Series B Preferred Stock automatically converted into shares of the Issuer's Common Stock on a 1:1 basis upon the closing of the Issuer's initial public offering. These securities had no expiration date.

2. Represents securities held directly by BCPE Perseus Investor, LP ("BCPE Perseus").

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

	See signatures included in Exhibit 99.1	04/20/2026
	** Signature of Reporting Person	Date
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.
* Form 4: SEC 1474 (03-26)

FAQ

What did Bain Capital–affiliated entities report in this Form 4 for Kailera Therapeutics (KLRA)?

They reported that BCPE Perseus Investor, LP acquired additional Kailera Therapeutics common stock. This included an open-market purchase of 8,398,438 shares at $16.00 per share and the automatic conversion of 17,857,143 Series B Preferred shares into common stock upon the IPO closing.

How many Kailera Therapeutics (KLRA) shares were bought in the open market?

BCPE Perseus Investor, LP reported an open-market purchase of 8,398,438 Kailera Therapeutics common shares at $16.00 per share. This transaction increased a reported indirect common stock holding line to 26,255,581 shares following the purchase, according to the Form 4 disclosure.

What happened to Kailera Therapeutics’ Series B Preferred Stock held by BCPE Perseus?

Each share of Series B Preferred Stock automatically converted into common stock on a 1:1 basis at the closing of Kailera’s initial public offering. This produced 17,857,143 common shares and reduced the reported Series B Preferred Stock position to zero, eliminating that derivative holding.

Who actually holds the Kailera Therapeutics (KLRA) shares reported in this Form 4?

The securities are held directly by BCPE Perseus Investor, LP. Bain Capital Investors, LLC and related Bain Capital funds may be deemed to share voting and dispositive power but each disclaims beneficial ownership of those securities except to the extent of its pecuniary interest.

Did this Form 4 show any sales of Kailera Therapeutics (KLRA) shares?

No sales were reported. The Form 4 shows an open-market purchase of 8,398,438 Kailera common shares at $16.00 and a conversion of 17,857,143 Series B Preferred shares into common, with the preferred stock position falling to zero afterward.