---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-26-374788"
form_type: "8-K"
ticker: "SPRO"
cik: "0001701108"
company_name: "Spero Therapeutics, Inc."
filed_at: "2026-08-28T21:25:56+00:00"
generated_at: "2026-08-28T21:28:10.874276+00:00"
event_type: "other_material"
sentiment: "neutral"
materiality_score: 0.5
calibrated_materiality_score: 0.5
confidence: "high"
source: SEC EDGAR
---

# Spero enters $100M ATM facility with Jefferies, terminates Cantor ATM

## Summary
- Sale Agreement with Jefferies LLC enables up to $100M of common stock in at-the-market offerings once S-3 is effective.
- Registration statement on Form S-3 for up to $300M in securities filed Aug 28, 2026; not yet effective, no sales permitted until then.
- Jefferies to receive up to 3.0% of gross proceeds for shares sold under the agreement.
- Terminated Cantor Fitzgerald ATM agreement effective Aug 28, 2026; no shares sold under it in FY2024 or FY2025, no penalties incurred.

## SEC filing metadata
- accession: 0001193125-26-374788
- form_type: 8-K
- ticker: SPRO
- cik: 0001701108
- company_name: Spero Therapeutics, Inc.
- filed_at: 2026-08-28T21:25:56+00:00
- event_type: other_material
- sentiment: neutral
- materiality_score: 0.5
- calibrated_materiality_score: 0.5
- confidence: high
- sec_items: 1.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1701108/000119312526374788/0001193125-26-374788-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1701108/000119312526374788/d145223d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-26-374788
- JSON: https://secwatch.observer/filing/0001193125-26-374788.json
- Plain text: https://secwatch.observer/filing/0001193125-26-374788.txt

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