OrbiMed buys 625K BlossomHill IPO shares at $16

BlossomHill Therapeutics, Inc. (BLSM) reported insider activity by OrbiMed-affiliated entities in connection with its initial public offering on August 10, 2026.

Rhea-AI Filing Summary

BlossomHill Therapeutics, Inc. (BLSM) reported insider activity by OrbiMed-affiliated entities in connection with its initial public offering on August 10, 2026. OrbiMed Private Investments VIII, LP converted 1,039,996 shares of Series A Preferred Stock and 1,049,283 shares of Series B Preferred Stock into an equal number of common shares upon the IPO closing, without payment of consideration. In addition, it purchased 625,000 common shares at 16.0000 per share in the IPO. The reported OrbiMed entities may be deemed to share voting and investment power over these securities through their control relationships and each disclaims beneficial ownership beyond its pecuniary interest.

Insider Trade Summary

Net Buyer: 625,000 shares

Net Buy 5 txns

Insider ORBIMED ADVISORS LLC, OrbiMed Capital GP VIII LLC

Role Director | Director

Bought 625,000 shs ($10.00M)

Type	Security	Shares	Price	Value
Conversion	Series A Preferred Stock F1, F3, F4	1,039,996	$0.00	$0.00
Conversion	Series B Preferred Stock F1, F3, F4	1,049,283	$0.00	$0.00
Conversion	Common Stock F1, F3, F4	1,039,996	--	--
Conversion	Common Stock F1, F3, F4	1,049,283	--	--
Purchase	Common Stock F2, F3, F4	625,000	$16.00	$10.00M

Holdings After Transaction: Series A Preferred Stock — 0 contracts (Indirect, See footnotes); Series B Preferred Stock — 0 contracts (Indirect, See footnotes); Common Stock — 2,714,279 shares (Indirect, See footnotes)

Footnotes (4)

1. F1. Each share of Series A Preferred Stock and Series B Preferred Stock (together, the "Preferred Stock") automatically converted into 1 share of the Issuer's Common Stock upon the closing of the Issuer's initial public offering on August 10, 2026 without payment of consideration. The Preferred Stock has no expiration date.
2. F2. Reflects shares of the Issuer's Common Stock purchased in the Issuer's initial public offering.
3. F3. These securities are held directly by OrbiMed Private Investments VIII, LP ("OPI VIII"). OrbiMed Capital GP VIII LLC ("GP VIII") is the general partner of OPI VIII. OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of GP VIII. By virtue of such relationships, GP VIII and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VIII and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, W. Carter Neild, and Geoffrey C. Hsu, each of whom disclaims beneficial ownership of the shares held by OPI VIII.
4. F4. This report on Form 4 is jointly filed by OrbiMed Advisors and GP VIII. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. The Reporting Persons have designated Carl L. Gordon, a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any of such entity or person is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

Key Figures

Series A Preferred converted: 1,039,996 shares Series B Preferred converted: 1,049,283 shares Total preferred shares converted: 2,089,279 shares +2 more

5 metrics

Series A Preferred converted 1,039,996 shares Automatically converted into common stock upon BLSM IPO closing on August 10, 2026

Series B Preferred converted 1,049,283 shares Automatically converted into common stock upon BLSM IPO closing on August 10, 2026

Total preferred shares converted 2,089,279 shares Sum of Series A and B Preferred Stock converted into common stock at IPO

Common shares purchased 625,000 shares Common stock of BLSM purchased in the initial public offering

Purchase price 16.0000 per share Price paid for 625,000 BLSM common shares in the IPO

Key Terms

automatic conversion, initial public offering, beneficial ownership, pecuniary interest

4 terms

automatic conversion financial

"Each share of Series A Preferred Stock and Series B Preferred Stock ... automatically converted"

initial public offering financial

"converted into 1 share of the Issuer's Common Stock 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.

beneficial ownership financial

"may be deemed to have beneficial ownership over such securities"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

pecuniary interest financial

"except to the extent of its pecuniary interest therein, if any"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transactions were reported for BLSM by OrbiMed-related entities?

OrbiMed-affiliated entities reported automatic conversion of preferred stock into 2,089,279 BLSM common shares and a separate purchase of 625,000 common shares in the company’s initial public offering on August 10, 2026.

How many BLSM shares did OrbiMed entities purchase in the IPO and at what price?

OrbiMed Private Investments VIII, LP purchased 625,000 BLSM common shares at 16.0000 per share in the initial public offering. This purchase is in addition to shares received through automatic conversion of preferred stock at the IPO closing.

What preferred stock of BLSM was converted into common stock in these Form 4 transactions?

The filing reports conversion of 1,039,996 shares of Series A Preferred Stock and 1,049,283 shares of Series B Preferred Stock into an equal number of BLSM common shares. The conversion occurred automatically at the closing of the initial public offering without consideration.

Who holds the BLSM shares reported in this Form 4 filed by OrbiMed entities?

The securities are held directly by OrbiMed Private Investments VIII, LP. OrbiMed Capital GP VIII LLC and OrbiMed Advisors LLC may be deemed to have voting and investment power through control relationships, but each disclaims beneficial ownership beyond its pecuniary interest.

Did OrbiMed entities indicate full beneficial ownership of the reported BLSM shares?

No. The reporting persons state they may be deemed beneficial owners through control relationships but disclaim beneficial ownership of the securities for Section 16 purposes, except to the extent of any pecuniary interest they may have.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/20/2026 - 12:27 PM Accepted by SEC EDGAR 08/12/2026 - 04:43 PM Learn about SEC filing dates

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^*

ORBIMED ADVISORS LLC

(Last) (First) (Middle)

601 LEXINGTON AVENUE

54TH FLOOR

(Street)

NEW YORK NEW YORK 10022

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
BlossomHill Therapeutics, Inc. [ BLSM ]

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/10/2026

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	08/10/2026		C		1,039,996	A	(1)	1,039,996	I	See footnotes(3)(4)
Common Stock	08/10/2026		C		1,049,283	A	(1)	2,089,279	I	See footnotes(3)(4)
Common Stock	08/10/2026		P		625,000(2)	A	$16	2,714,279	I	See footnotes(3)(4)

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 A Preferred Stock	(1)	08/10/2026		C			1,039,996	(1)	(1)	Common Stock	1,039,996	$0	0	I	See footnotes(3)(4)
Series B Preferred Stock	(1)	08/10/2026		C			1,049,283	(1)	(1)	Common Stock	1,049,283	$0	0	I	See footnotes(3)(4)

1. Name and Address of Reporting Person^*

ORBIMED ADVISORS LLC

(Last) (First) (Middle)

601 LEXINGTON AVENUE

54TH FLOOR

(Street)

NEW YORK NEW YORK 10022

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

OrbiMed Capital GP VIII LLC

(Last) (First) (Middle)

601 LEXINGTON AVENUE

54TH FLOOR

(Street)

NEW YORK NEW YORK 10022-4629

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. Each share of Series A Preferred Stock and Series B Preferred Stock (together, the "Preferred Stock") automatically converted into 1 share of the Issuer's Common Stock upon the closing of the Issuer's initial public offering on August 10, 2026 without payment of consideration. The Preferred Stock has no expiration date.

2. Reflects shares of the Issuer's Common Stock purchased in the Issuer's initial public offering.

3. These securities are held directly by OrbiMed Private Investments VIII, LP ("OPI VIII"). OrbiMed Capital GP VIII LLC ("GP VIII") is the general partner of OPI VIII. OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of GP VIII. By virtue of such relationships, GP VIII and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VIII and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, W. Carter Neild, and Geoffrey C. Hsu, each of whom disclaims beneficial ownership of the shares held by OPI VIII.

4. This report on Form 4 is jointly filed by OrbiMed Advisors and GP VIII. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. The Reporting Persons have designated Carl L. Gordon, a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any of such entity or person is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

	/s/ Carl L. Gordon, Member of OrbiMed Advisors LLC	08/12/2026
	/s/ Carl L. Gordon, Member of OrbiMed Capital GP VIII LLC	08/12/2026
	** 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.
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* Form 4: SEC 1474 (03-26)