How much did Horizon3.ai raise in its Series E?

Horizon3.ai raised $250M in a Series E announced on 3 August 2026.

Who invested in Horizon3.ai's Series E?

The round was led by NightDragon, NEA.

What does Horizon3.ai do?

Horizon3.ai is a cybersecurity company specializing in Security Operations, founded in 2019 and headquartered in San Francisco, United States.

Funding record · 2026 / 08

Horizon3.ai raises $250M Series E for security operations

Announced 3 August 2026 · Recorded 8 September 2026 · Last verified 8 September 2026

Horizon3.ai, a security operations company based in San Francisco, United States, raised $250M in a Series E announced on 3 August 2026, led by NightDragon and NEA. Its disclosed equity funding is now $428.5M across 7 rounds.

Amount: $250M
Round: Series E
Announced: 3 August 2026
Lead investors: NightDragon, NEA
Valuation: $2Bdisclosed
Sources on record: 14wsj.com

From the source

Horizon3.ai raises $250M Series E

wsj.com · 3 August 2026 ↗

The Mandos read

What the record says about Horizon3.ai

Momentum 77 / 100 · Acceleratinglocked →
pillars in the platform
446 employees · up 5% last month · 59 open roleslocked →
history and breakdowns in the platform
Exit Readiness: Lowlocked →
Tested against 751 past exits in the Mandos record: 43% sat in Watch or Elevated 2 years before. Companies in Elevated exited at 3.1× the record's rate.
Buyers most often compare Horizon3.ai with Novee Security, Armadin and XBOW and 5 morelocked →
the full set in the platform

Funding history

Horizon3.ai funding on record

Horizon3.ai has raised $428.5M in priced equity. Its most recent round was a Series E in August 2026.

Latest round on record: Series E, Aug 2026.

Horizon3.ai funding on the profile →

In the platform

The round is the fact. The read is the product.

Every round, investor and correction for Horizon3.ai, the competitors buyers weigh it against, hiring by department, and an alert when the next thing happens.

Explore Horizon3.ai in Mandos Request full profile

The same record answers in Claude, ChatGPT and Cursor through the Mandos MCP server.

The Mandos Brief

Cybersecurity funding, deals and moves, every Monday.

FAQ

Questions people ask

How much did Horizon3.ai raise in its Series E?: Horizon3.ai raised $250M in a Series E announced on 3 August 2026.
Who invested in Horizon3.ai's Series E?: The round was led by NightDragon, NEA.
What does Horizon3.ai do?: Horizon3.ai is a cybersecurity company specializing in Security Operations, founded in 2019 and headquartered in San Francisco, United States.