Investor · BROOKLINE, MA

David A. Sontag

Open David in the network graph →

Filings

2

SEC Form D

Connections

2

co-filers

Capital

$55.6M

across filings

Active

Apr 2025

to Dec 2025

Most-connected co-filers (2)

Lynne A. O'Keefe · BROOKLINE, MA2 shared Anthony A. Philippakis · Boston, MA2 shared

Recent filings (2)

Layer Health, Inc.Dec 2025 · 5 co-filers$29.5M Layer Health, Inc.Dec 2025 · 5 co-filers$29.5M Layer Health, Inc.Apr 2025 · 5 co-filers$26.0M Layer Health, Inc.Apr 2025 · 5 co-filers$26.0M

Derived from public SEC Form D (Reg D) filings; entities resolved probabilistically. See David in the interactive graph →