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Latigo Biotherapeutics (LTGO) director lists IPO-linked fund stake

(Neutral)
(Neutral)
Form Type
3

Rhea-AI Filing Summary

Latigo Biotherapeutics, Inc. (LTGO) received an initial ownership report from Beth C. Seidenberg, who is a director and more than 10% owner. The filing lists only indirect holdings in preferred stock series and a convertible note, held through Westlake BioPartners funds and an opportunity fund, each convertible into shares of common stock, generally upon the closing of Latigo’s initial public offering. Seidenberg, as sole managing director of the relevant general partners, has voting and dispositive power over these fund-held securities but disclaims Section 16 beneficial ownership except to the extent of her pecuniary interest.

Positive

  • None.

Negative

  • None.
Insider SEIDENBERG BETH C
Role Director, 10% Owner
Type Security Shares Price Value
holding Series Seed Convertible Preferred Stock F4, F1 -- -- --
holding Series A Convertible Preferred Stock F4, F1 -- -- --
holding Series A-2 Convertible Preferred Stock F4, F1 -- -- --
holding Series A-2 Convertible Preferred Stock F4, F2 -- -- --
holding Series B Convertible Preferred Stock F4, F2 -- -- --
holding Series A-2 Convertible Preferred Stock F4, F3 -- -- --
holding Convertible Promissory Note F5, F2 -- -- --
holding Common Stock F1 -- -- --
holding Common Stock F2 -- -- --
holding Common Stock F3 -- -- --
Holdings After Transaction: Series Seed Convertible Preferred Stock — 938,979 shares (Indirect, See footnote); Series A Convertible Preferred Stock — 3,547,842 shares (Indirect, See footnote); Series A-2 Convertible Preferred Stock — 6,558,564 shares (Indirect, See footnote); Series B Convertible Preferred Stock — 1,484,401 shares (Indirect, See footnote); Convertible Promissory Note — 165,519 shares (Indirect, See footnote); Common Stock — 504,364 shares (Indirect, See footnote)
Footnotes (5)
  1. F1. Shares held directly by Westlake BioPartners Fund I, L.P. (Fund I). The general partner of Fund I is Westlake BioPartners GP I, LLC (GP I). GP I may be deemed to share voting and dispositive power with regard to the shares held directly by Fund I. The Reporting Person is the sole managing director of GP I and has voting and dispositive power over the shares held by Fund I. The Reporting Person disclaims Section 16 beneficial ownership of the shares reported herein except to the extent of her pecuniary interest therein, if any, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of any of the reported shares for purposes of Section 16 or any other purpose.
  2. F2. Shares held directly by Westlake BioPartners Fund II, L.P. (Fund II). The general partner of Fund II is Westlake BioPartners GP II, LLC (GP II). GP II may be deemed to share voting and dispositive power with regard to the shares held directly by Fund II. The Reporting Person is the sole managing director of GP II and has voting and dispositive power over the shares held by Fund II. The Reporting Person disclaims Section 16 beneficial ownership of the shares reported herein except to the extent of her pecuniary interest therein, if any, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of any of the reported shares for purposes of Section 16 or any other purpose.
  3. F3. Shares held directly by Westlake BioPartners Opportunity Fund I, L.P. (Opportunity Fund). The general partner of Opportunity Fund is Westlake BioPartners Opportunity GP I, LLC (Opportunity GP). Opportunity GP may be deemed to share voting and dispositive power with regard to the shares held directly by Opportunity Fund. The Reporting Person is the sole managing director of Opportunity GP and has voting and dispositive power over the shares held by Opportunity Fund. The Reporting Person disclaims Section 16 beneficial ownership of the shares reported herein except to the extent of her pecuniary interest therein, if any, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of any of the reported shares for purposes of Section 16 or any other purpose.
  4. F4. Each share of Series Seed Convertible Preferred Stock, Series A Convertible Preferred Stock, Series A-2 Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the "Preferred Stock") will automatically convert into 1 share of Common Stock upon the closing of the Issuer's initial public offering without payment of further consideration. Share numbers give effect to such conversion. The Preferred Stock has no expiration date.
  5. F5. Reflects a convertible note that is convertible into shares of Common Stock of the Issuer. The convertible note has a maturity date of June 17, 2027. The principal amount of the convertible note together with any accrued but unpaid interest will be automatically converted into shares of Common Stock of the Issuer upon the closing of the Issuer's initial public offering at a conversion price equal to the initial public offering price of the Issuer's common stock.
Underlying Shares - Series Seed Convertible Preferred Stock 938,979 shares of Common Stock Shares underlying Series Seed Convertible Preferred Stock held indirectly
Underlying Shares - Series A Convertible Preferred Stock 3,547,842 shares of Common Stock Shares underlying Series A Convertible Preferred Stock held indirectly
Underlying Shares - Series A-2 Convertible Preferred Stock (Fund I) 1,027,635 shares of Common Stock Shares underlying one Series A-2 position held indirectly
Underlying Shares - Series A-2 Convertible Preferred Stock (Fund II) 3,464,072 shares of Common Stock Shares underlying another Series A-2 position held indirectly
Underlying Shares - Series B Convertible Preferred Stock 1,484,401 shares of Common Stock Shares underlying Series B Convertible Preferred Stock held indirectly
Underlying Shares - Series A-2 Convertible Preferred Stock (Opportunity Fund) 2,066,857 shares of Common Stock Shares underlying Series A-2 Convertible Preferred Stock held via Opportunity Fund
Underlying Shares - Convertible Promissory Note 165,519 shares of Common Stock Shares of common stock underlying the reported convertible note
Series Seed Convertible Preferred Stock financial
"security_title "Series Seed Convertible Preferred Stock" will automatically convert"
Convertible Promissory Note financial
"Reflects a convertible note that is convertible into shares of Common Stock"
A convertible promissory note is a loan a company takes now that can later be turned into shares instead of being repaid in cash. Think of it as lending money with the option to accept ownership in the business down the road; that matters to investors because it affects who gets paid first, how much ownership existing shareholders keep, and the company’s future valuation and cash needs. Terms such as conversion price, interest and maturity determine the financial impact.
Section 16 beneficial ownership regulatory
"The Reporting Person disclaims Section 16 beneficial ownership of the shares"
voting and dispositive power financial
"may be deemed to share voting and dispositive power with regard to the shares"
initial public offering financial
"will automatically convert into 1 share of 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.

FAQ

What does Beth C. Seidenberg report owning in LTGO on this Form 3?

She reports only indirect holdings in various preferred stock series and a convertible promissory note of Latigo Biotherapeutics, Inc., each convertible into shares of Common Stock, with all securities held through Westlake BioPartners funds and an opportunity fund, not in her name personally.

How many LTGO common shares underlie the Series Seed Convertible Preferred Stock?

The Series Seed Convertible Preferred Stock reported by Beth C. Seidenberg is convertible into 938,979 shares of Latigo Biotherapeutics, Inc. common stock, with the share number already giving effect to the automatic conversion terms described for the preferred stock upon the company’s initial public offering.

What LTGO common shares are tied to the convertible promissory note in this filing?

The convertible promissory note reported is convertible into 165,519 shares of Latigo Biotherapeutics, Inc. common stock. The note’s principal plus accrued but unpaid interest will convert automatically into common shares upon the company’s initial public offering at a price equal to the IPO price.

How does the preferred stock reported convert into LTGO common stock?

Each share of Preferred Stock (Series Seed, Series A, Series A-2, and Series B) will automatically convert into 1 share of Common Stock upon the closing of Latigo Biotherapeutics, Inc.’s initial public offering, without further consideration, and the reported share numbers already reflect this conversion.

Does Beth C. Seidenberg claim full beneficial ownership of the LTGO shares reported?

No. She disclaims Section 16 beneficial ownership of the shares held by the Westlake funds and the opportunity fund, except to the extent of her pecuniary interest, and states that inclusion of these shares is not an admission of beneficial ownership for Section 16 or any other purpose.

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SEC Form 3
FORM 3UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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:3235-0104
Estimated average burden
hours per response:0.5
1. Name and Address of Reporting Person*
SEIDENBERG BETH C

(Last)(First)(Middle)
C/O LATIGO BIOTHERAPEUTICS, INC.
1300 RANCHO CONEJO BLVD., SUITE 305

(Street)
THOUSAND OAKS CALIFORNIA 91320

(City)(State)(Zip)

UNITED STATES

(Country)
2. Date of Event Requiring Statement (Month/Day/Year)
08/06/2026
3. Issuer Name and Ticker or Trading Symbol
Latigo Biotherapeutics, Inc. [ LTGO ]
3a. Foreign Trading Symbol
5. If Amendment, Date of Original Filed (Month/Day/Year)
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
XDirectorX10% Owner
Officer (give title below)Other (specify below)
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm filed by One Reporting Person
Form filed by More than One Reporting Person
Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock429,553ISee footnote(1)
Common Stock46,855ISee footnote(2)
Common Stock27,956ISee footnote(3)
Table II - Derivative Securities Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4) 2. Date Exercisable and Expiration Date (Month/Day/Year)3. Title and Amount of Securities Underlying Derivative Security (Instr. 4) 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 6. Nature of Indirect Beneficial Ownership (Instr. 5)
Date ExercisableExpiration DateTitleAmount or Number of Shares
Series Seed Convertible Preferred Stock (4) (4)Common Stock938,979(4)ISee footnote(1)
Series A Convertible Preferred Stock (4) (4)Common Stock3,547,842(4)ISee footnote(1)
Series A-2 Convertible Preferred Stock (4) (4)Common Stock1,027,635(4)ISee footnote(1)
Series A-2 Convertible Preferred Stock (4) (4)Common Stock3,464,072(4)ISee footnote(2)
Series B Convertible Preferred Stock (4) (4)Common Stock1,484,401(4)ISee footnote(2)
Series A-2 Convertible Preferred Stock (4) (4)Common Stock2,066,857(4)ISee footnote(3)
Convertible Promissory Note (5) (5)Common Stock165,519(5)ISee footnote(2)
Explanation of Responses:
1. Shares held directly by Westlake BioPartners Fund I, L.P. (Fund I). The general partner of Fund I is Westlake BioPartners GP I, LLC (GP I). GP I may be deemed to share voting and dispositive power with regard to the shares held directly by Fund I. The Reporting Person is the sole managing director of GP I and has voting and dispositive power over the shares held by Fund I. The Reporting Person disclaims Section 16 beneficial ownership of the shares reported herein except to the extent of her pecuniary interest therein, if any, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of any of the reported shares for purposes of Section 16 or any other purpose.
2. Shares held directly by Westlake BioPartners Fund II, L.P. (Fund II). The general partner of Fund II is Westlake BioPartners GP II, LLC (GP II). GP II may be deemed to share voting and dispositive power with regard to the shares held directly by Fund II. The Reporting Person is the sole managing director of GP II and has voting and dispositive power over the shares held by Fund II. The Reporting Person disclaims Section 16 beneficial ownership of the shares reported herein except to the extent of her pecuniary interest therein, if any, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of any of the reported shares for purposes of Section 16 or any other purpose.
3. Shares held directly by Westlake BioPartners Opportunity Fund I, L.P. (Opportunity Fund). The general partner of Opportunity Fund is Westlake BioPartners Opportunity GP I, LLC (Opportunity GP). Opportunity GP may be deemed to share voting and dispositive power with regard to the shares held directly by Opportunity Fund. The Reporting Person is the sole managing director of Opportunity GP and has voting and dispositive power over the shares held by Opportunity Fund. The Reporting Person disclaims Section 16 beneficial ownership of the shares reported herein except to the extent of her pecuniary interest therein, if any, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of any of the reported shares for purposes of Section 16 or any other purpose.
4. Each share of Series Seed Convertible Preferred Stock, Series A Convertible Preferred Stock, Series A-2 Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the "Preferred Stock") will automatically convert into 1 share of Common Stock upon the closing of the Issuer's initial public offering without payment of further consideration. Share numbers give effect to such conversion. The Preferred Stock has no expiration date.
5. Reflects a convertible note that is convertible into shares of Common Stock of the Issuer. The convertible note has a maturity date of June 17, 2027. The principal amount of the convertible note together with any accrued but unpaid interest will be automatically converted into shares of Common Stock of the Issuer upon the closing of the Issuer's initial public offering at a conversion price equal to the initial public offering price of the Issuer's common stock.
/s/ Sabrina Nieder, Attorney-in-Fact08/06/2026
** Signature of Reporting PersonDate
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 5 (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 3: SEC 1473 (03-26)