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BlossomHill lands OrbiMed 8.9% equity stake

(Moderate)
(Neutral)
Form Type
SCHEDULE 13D

Rhea-AI Filing Summary

BlossomHill Therapeutics, Inc. (BLSM) is reported to have a significant shareholder group led by OrbiMed Advisors LLC and OrbiMed Capital GP VIII LLC, which together report beneficial ownership of 2,714,279 shares of common stock, representing 8.9% of outstanding shares.

These shares come from purchases of Series A and Series B preferred stock that converted 1-for-1 into common upon the IPO, plus 625,000 shares bought in the IPO at $16.00 per share. OrbiMed entities share voting and dispositive power over these shares through OrbiMed Private Investments VIII, LP, and OrbiMed executive Carl L. Gordon serves on BlossomHill’s board.

OPI VIII also holds registration rights (Form S-1, piggyback, and Form S-3) and is party to a 180‑day lock-up following the IPO, limiting sales and registration demands during that period. The filing states the position is held for investment purposes, with no current plan to change control or corporate structure.

Positive

  • None.

Negative

  • None.

Filing Explained

This Schedule 13D places OrbiMed’s disclosure in the ownership-above-5% framework used when a holder may seek to influence control; it states no current plan to change control, but notes that board member Carl L. Gordon means OrbiMed may have the ability to affect or influence control.

Beneficial ownership 2,714,279 shares Shares of BlossomHill Therapeutics common stock held by OPI VIII as of the filing date
Ownership percentage 8.9% Portion of BlossomHill’s 30,643,660 outstanding shares represented by OPI VIII’s holdings
Shares outstanding 30,643,660 shares Outstanding BlossomHill common shares as set forth in the August 7, 2026 prospectus
IPO purchase 625,000 shares at $16.00 per share Shares purchased by OPI VIII in BlossomHill’s IPO
Series A preferred purchased 1,039,996 shares Series A preferred stock of BlossomHill acquired by OPI VIII in March 2021
Series B preferred purchased 1,049,283 shares Series B preferred stock of BlossomHill acquired by OPI VIII in December 2023
Form S-3 request threshold 30% of registrable securities and $1 million Holders of at least 30% may request Form S-3 if expected net proceeds ≥ $1 million
Lock-up period 180 days Duration after the final IPO prospectus during which OPI VIII and Gordon agreed to restrictions
Schedule 13D regulatory
"This Statement on relates to the acquisition of Shares by the Reporting Persons."
A Schedule 13D is a legal document that investors file with regulators when they buy a large enough stake in a company to potentially influence its management or decisions. It provides details about the investor’s intention, ownership stake, and plans, helping other investors understand who is gaining control and what their motives might be.
beneficial owners financial
"may be deemed directly or indirectly, including by reason of their mutual affiliation, to be the beneficial owners of the Shares"
Beneficial owners are the people or entities that actually enjoy the economic benefits and control of shares or other assets, even when legal title is held by someone else such as a broker, custodian or trustee. Investors pay attention because beneficial owners hold the real voting power, receive dividends and can influence strategy and takeover outcomes — like the driver of a car who uses and maintains it while the bank holds the title — so disclosure shows who truly controls and benefits.
piggyback registration rights regulatory
"the holders of such Shares will be entitled to certain piggyback registration rights allowing the holder to include their Shares"
A contractual right that lets existing shareholders join a company’s planned public sale of stock so they can sell their own shares at the same time under the same paperwork. It matters to investors because it gives insiders and early holders an easier, often faster way to convert shares to cash, while also potentially increasing the number of shares offered and affecting the share price — like catching a scheduled bus instead of hiring a private ride to get where you need to go.
Form S-3 registration rights regulatory
"will be entitled to certain Form S-3 registration rights."
lock-up agreement regulatory
"entered into a lock-up agreement (the "Lock-Up Agreement") with the Issuer's underwriters"
A lock-up agreement is a contract that prevents company insiders and early investors from selling their shares for a fixed period after a stock sale, often after an initial public offering. It matters to investors because it temporarily limits the number of shares that can hit the market, which can keep the share price steadier; when the lock-up ends, a sudden increase in available shares can create extra volatility, revealing insiders’ confidence or lack thereof.

FAQ

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

How much of BlossomHill Therapeutics (BLSM) does OrbiMed beneficially own?

OrbiMed, through OrbiMed Private Investments VIII, LP, reports beneficial ownership of 2,714,279 shares of BlossomHill Therapeutics common stock, representing approximately 8.9% of the 30,643,660 shares outstanding cited in the company’s August 7, 2026 prospectus.

How did OrbiMed acquire its stake in BlossomHill Therapeutics (BLSM)?

OrbiMed’s funds purchased 1,039,996 Series A preferred and 1,049,283 Series B preferred shares, which converted 1‑for‑1 into common at the IPO, and bought an additional 625,000 common shares in the IPO at $16.00 per share.

What voting control does OrbiMed have over BlossomHill Therapeutics (BLSM) shares?

OrbiMed Advisors and OrbiMed Capital GP VIII share power to direct the vote and disposition of 2,714,279 BlossomHill shares held by OrbiMed Private Investments VIII, LP, and therefore may be deemed beneficial owners of that 8.9% stake through their management and general partner roles.

Does OrbiMed have board representation at BlossomHill Therapeutics (BLSM)?

Yes. Carl L. Gordon, a member of OrbiMed Advisors, serves on BlossomHill Therapeutics’ board of directors. The filing notes this relationship means OrbiMed Advisors and OrbiMed GP may have the ability to affect and influence control of the issuer.

What registration rights does OrbiMed have for its BlossomHill Therapeutics (BLSM) shares?

Under a December 28, 2023 Investors’ Rights Agreement, OrbiMed’s fund holds Form S‑1 demand, piggyback, and Form S‑3 registration rights, including S‑1 demands by holders of at least 70% of registrable securities and S‑3 demands by holders of at least 30%, subject to conditions.

Is OrbiMed restricted from selling BlossomHill Therapeutics (BLSM) shares after the IPO?

Yes. OrbiMed’s fund OPI VIII and Carl L. Gordon entered a lock-up agreement restricting most transfers, hedging, and registration demands for 180 days after the date of the final IPO prospectus, subject to limited exceptions described in the agreement.

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

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Learn about SEC filing dates





095130100

(CUSIP Number)
OrbiMed Advisors LLC
601 Lexington Avenue, 54th Floor
New York, NY, 10022
(212) 739-6400


OrbiMed Capital GP VIII LLC
601 Lexington Avenue, 54th Floor
New York, NY, 10022
(212) 739-6400

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)
08/10/2026

(Date of Event Which Requires Filing of This Statement)


If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).




schemaVersion:


SCHEDULE 13D






SCHEDULE 13D






SCHEDULE 13D


ORBIMED ADVISORS LLC
Signature:/s/ Carl L. Gordon
Name/Title:Carl L. Gordon/Member
Date:08/18/2026
OrbiMed Capital GP VIII LLC
Signature:/s/ Carl L. Gordon
Name/Title:Carl L. Gordon/Member of OrbiMed Advisors LLC
Date:08/18/2026

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