Marathon Venture Capital Research
Investment Thesis
Marathon Venture Capital is an Athens-based seed-stage fund that backs Greek and European founders building technology companies. Its tagline is that it backs founders on day one and stays for the long run. The firm frames a founder's job as three tasks: set the vision, build the team that delivers it, and secure the resources to make it happen. Marathon says it helps on all three. The team describes itself as operators first, people who have built and sold companies, shipped products and raised money.
The portfolio is sector-agnostic in form but clusters around deep-tech and B2B software: developer tools and observability (Netdata, NoFire AI, Straion, Lenses), security (Hack The Box, Verno Labs, Code BGP), robotics and automation (Bota Systems, Progressive Robotics), defense and drones (Delian Alliance Industries, Velos Rotors), energy (SMPnet), agriculture (Augmenta, Centaur Analytics), construction and real estate (Archiboost, Dataform Lab, Ariadne), pharma R&D (PolyModels Hub) and AI (Causaly, Connectly).
Stage Focus
Marathon leads seed rounds and offers what it calls industry-standard, founder-friendly terms. It publishes its term sheets (US and Greece), a seed round model, a seed pitch deck and a legal package on its resources page. Third-party profiles list pre-seed through Series A. It follows on to hold its pro-rata in Series A and Series B rounds.
Check Size
The firm does not state a check size on its site. Press on its portfolio rounds suggests it leads seed rounds in the low single-digit millions of euros. For example, press snippets describe a $2.5M seed for NoFire AI led by Marathon. Check size is left unset in the structured record because no firm-published figure was found.
Lead Tendency
Marathon states that it leads seed rounds. Lead tendency is recorded as leads.
Recent Activity
- November 2026: Archiboost AI raised $6.2M; Marathon is an investor and partner Alex Alexakis wrote the announcement.
- August 2026: Pitchbook's annual report for 2025 named Marathon a top 10 fund in Europe.
- May 2026: Marathon led the seed round for NoFire AI, an AI SRE tool for root-cause analysis (post by Panos Papadopoulos).
- February 2026: Marathon invested in Straion, a governance layer for AI coding agents.
- May 2025: Fund III closed at EUR 75M in an oversubscribed single closing, with EUR 20M from the European Investment Fund.
The firm has raised more than EUR 180M across three funds since 2017. Fund III is actively deploying.
Portfolio Highlights
The site lists 24 companies since 2017 and 5 exits (the portfolio page marks four exits explicitly):
- Augmenta, acquired by CNH Industrial
- Lenses, acquired by Celonis
- Code BGP, acquired by Cisco
- InAccel, acquired by Intel
Other notable companies: Causaly (biomedical AI, 2018), Hack The Box (cybersecurity training, 2019), LearnWorlds (e-learning SaaS, 2019), Netdata (monitoring, 2018) and Delian Alliance Industries (defense, 2021). Avrio is listed as inactive.
Team
- George Tziralis, Partner: helped build the Greek startup ecosystem from scratch; long-distance runner.
- Alex Alexakis, Partner: former product manager at high-growth startups; writes the Startup Pirate newsletter.
- Panos Papadopoulos, Partner: engineer turned founder turned investor.
- Sofia Tsapara, VP Finance: runs finance, operations and compliance.
Decision Process
Three partners make investment decisions together. The firm invites founders to reach out before they feel fully ready, at [email protected], and says it prefers to engage early and watch founders perform. Marathon II was supported by InnovFin Equity with EU backing, and Fund III by the EIF.
Founder Preferences
Marathon backs technical and operator founders from Greece, the Greek diaspora and Europe, often at the earliest stage. Founder testimonials (Hack The Box, Netdata, Lenses) stress time spent with founders, recruiting help, product and go-to-market strategy, fundraising introductions to later-stage funds, and long-term personal support. The firm also runs community events such as Open Coffee Athens and Greeks In Tech in San Francisco and London.
Geographic Focus
Greece first, then the wider European market and the Greek diaspora, including the US. Offices and events: Athens, with events across 25 countries.
Gaps
No published check size, no stated sector exclusions, and no per-company stage or date on the portfolio page. Portfolio company domains were left null where they could not be confirmed from the page.