---
schema_version: "secwatch.filing_event.v1"
accession: "0001537435-25-000008"
form_type: "8-K"
ticker: "TGEN"
cik: "0001537435"
company_name: "TECOGEN INC."
filed_at: "2025-02-19T23:59:59+00:00"
generated_at: "2026-05-26T11:48:18.411238+00:00"
event_type: "debt"
sentiment: "neutral"
materiality_score: 0.35
calibrated_materiality_score: 0.35
confidence: "high"
source: SEC EDGAR
---

# Tecogen extends $1M promissory notes to lead director; option for stock conversion

## Summary
- Two $500k promissory notes held by lead director John N. Hatsopoulos amended.
- Maturity extended to July 31, 2026 for both notes (originally Oct 2023 and July 2024).
- Hatsopoulos may elect repayment in cash or common stock at 30-day avg closing price.
- No new funds raised; notes remain outstanding with no interest-rate change disclosed.

## SEC filing metadata
- accession: 0001537435-25-000008
- form_type: 8-K
- ticker: TGEN
- cik: 0001537435
- company_name: TECOGEN INC.
- filed_at: 2025-02-19T23:59:59+00:00
- event_type: debt
- sentiment: neutral
- materiality_score: 0.35
- calibrated_materiality_score: 0.35
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1537435/000153743525000008/0001537435-25-000008-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1537435/000153743525000008/tgen-20250219.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001537435-25-000008
- JSON: https://secwatch.observer/filing/0001537435-25-000008.json
- Plain text: https://secwatch.observer/filing/0001537435-25-000008.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.