Form
SCHEDULE 13D/A
Active or control-oriented beneficial ownership filing.
Norwest Venture Partners XVI, LP - 26 Sep 2025 SCHEDULE 13D/A Report for MBX BIOSCIENCES, INC. Common Stock, $0.0001 par value per share (MBX)
- Filing manager
- Norwest Venture Partners XVI, LP
- Reporting owner
- Tiba Aynechi
- Beneficially owned shares
- 2,140,989 shares
- Large-stake signal
-
Ownership
4.8%Beneficial ownership of this reported class.
Shares
2,140,989 sharesShares beneficially owned as disclosed.
Event date
26 Sep 2025Date tied to the ownership event or amendment.
Accepted by SEC
30 Sep 2025EDGAR acceptance date.
How to read this large-stake filing
- Schedule 13D/G filings focus on beneficial ownership stakes, not a full portfolio.
- Compare this filing with the holder history and issuer page before treating the percentage as a current position.
- Use amendments to understand whether the disclosed stake increased, decreased, or changed reporting status.
- Class ownership
- 4.8%
- Symbol
- MBX
- Shares outstanding
- 44,603,938 shares
- SEC form
- SCHEDULE 13D/A
- Accepted by SEC
- 30 Sep 2025, 18:15:45 UTC
- Event date
- 26 Sep 2025
- Source filing
- View source filing
Ownership signal
CIK-linked ownership evidence from parsed SEC filings.
2 signals
Subject security
Names, identifiers, and filing context for this profile.
2 source fields
Source evidence
Original filing metadata and source links for verification.
4 source fields
Key filing fact
Norwest Venture Partners XVI, LP disclosed 4.8% ownership in MBX BIOSCIENCES, INC. Common Stock, $0.0001 par value per share (MBX) on 26 Sep 2025.
Key facts
- Norwest Venture Partners XVI, LP filed SCHEDULE 13D/A for MBX BIOSCIENCES, INC. Common Stock, $0.0001 par value per share (MBX).
- Disclosed ownership: 4.8%.
- Date of event: 26 Sep 2025.
Change
- No earlier schedule filing is available for direct comparison.
- Current filing was accepted on 30 Sep 2025, 18:15.
Research use
- This page turns one Schedule 13D/G filing into a quick large-stake read before the raw reporting-person rows.
- Use the linked SEC filing as the source of truth for ownership percentages, shares, and reporting-party details.
Evidence
Backed by Schedule 13D/13G
View source filing
Beneficial ownership values are sourced from the original SEC Schedule 13D/13G filing.
Reporting persons
Disclosed reporting parties (6)
Names, ownership percentages, voting power, signatures, titles, and CIKs as disclosed in this Schedule 13D/G filing.
| Name | Ownership | Shares owned | Sole voting power | Shared voting power | Signature | Title | CIK |
|---|---|---|---|---|---|---|---|
| Norwest Venture Partners XVI, LP | 4.8% | 2,136,335 | 0 | 2,136,335 | /s/ Matthew De Dominicis | By Genesis VC Partners XVI, LLC, its General Partner, By NVP Associates, LLC, its Managing Member, By Matthew De Dominicis, Chief Financial Officer | 0001876200 |
| Genesis VC Partners XVI, LLC | 4.8% | 2,136,335 | 0 | 2,136,335 | /s/ Matthew De Dominicis | By NVP Associates, LLC, its Managing Member, By Matthew De Dominicis, Chief Financial Officer | |
| NVP Associates, LLC | 4.8% | 2,136,335 | 0 | 2,136,335 | /s/ Matthew De Dominicis | By Matthew De Dominicis, Chief Financial Officer | 0001545692 |
| Jeffrey Crowe | 4.8% | 2,136,335 | 0 | 2,136,335 | /s/ Matthew De Dominicis | By Matthew De Dominicis, Attorney-in-fact | 0001535261 |
| Jon Erik Kossow | 4.8% | 2,136,335 | 0 | 2,136,335 | /s/ Matthew De Dominicis | By Matthew De Dominicis, Attorney-in-fact | 0001726084 |
| Tiba Aynechi | 4.8% | 2,140,989 | 4,654 | 2,136,335 | /s/ Matthew De Dominicis | By Matthew De Dominicis, Attorney-in-fact | 0001669220 |
CIK / CUSIP context first