Steve O'Brien - Mantis Venture Capital Research Document
Executive Summary
Steve O'Brien is the Investor & Head of Platform at Mantis Venture Capital, a Santa Monica-based early-stage venture capital firm with $225M in assets under management across three funds. O'Brien plays a dual role as both a principal investor focused on deal sourcing and as the strategic lead for Mantis's platform operations, including brand, investor relations, recruitment support, and data-driven fund operations. He serves on the Mantis Investment Committee alongside the four general partners and is recognized as one of the firm's key operational strategists.
Investment Thesis & Philosophy
Steve O'Brien operates within Mantis's investment thesis of backing passionate founders building early-stage technology startups. O'Brien seeks to partner with entrepreneurs who demonstrate deep commitment and domain expertise in their industries. His hands-on approach emphasizes actively engaging across multiple value-add dimensions beyond capital provision—specifically marketing, recruitment, strategic partnerships, and creative brand storytelling.
Investment Stage & Check Size
Pre-seed and Seed stage investments are O'Brien's primary focus, with some Series A participation. Mantis Fund III's $100M size and 130+ portfolio companies suggest average check sizes in the $500K-$2M range for pre-seed/seed rounds. The firm has maintained consistent deployment velocity across three funds raised over approximately 6 years (2019-2025), with 170+ total investments.
Lead vs. Follow Tendency
O'Brien and Mantis have a strong lead investor tendency, particularly at seed stage. Multiple portfolio founder testimonials emphasize Mantis's ability to actively source deals, win competitive allocations, and lead rounds. Mantis's track record includes 19 unicorns, 1 IPO, and 9 acquisitions from their portfolio, with Fund I currently performing in the top decile of its vintage (2020 cohort).
Decision Process & Timeline
Investment decisions follow a partnership model with input from multiple stakeholders. O'Brien sits on the Mantis Investment Committee alongside the four general partners (Alex Pall, Drew Taggart, Jeffrey Evans, Milan Koch), plus vertical specialists Saveena Mandadi (cybersecurity), Caroline Menkes (healthcare), and Gaurav Bhogale (AI/Infrastructure). Founder testimonials suggest a 2-3 week decision timeline at seed stage.
Portfolio & Recent Activity
170+ investments across three funds with particular strength in Fintech & Payments (MoonPay unicorn, Pipe, Kalshi), AI/ML Infrastructure (Additive AI, Factory AI, Rogo Data), Cybersecurity (Chainguard, iVerify, Edera), Healthcare Tech (Fellow, Journey, Rupa Health), Gaming & Creator Economy (Mythical Games, Stardust, Faraway), Enterprise Software (Incident.io, Superhuman, Rutter), and Frontier Tech (Shinkei, Apeel Sciences). Actively deploying capital from $100M Fund III (closed July 2025).
Platform & Operational Leadership
As Head of Platform, O'Brien oversees brand & communications, investor relations, and portfolio support platform. Recently led a strategic partnership with Palantir to power Mantis's internal data-driven operations, indicating modern, metrics-driven approach to fund operations. Coordinates recruitment & talent function and vertical expertise across the team.
Founder Preferences
O'Brien seeks founders with: (1) Passion & Commitment to their industries; (2) Domain Expertise and entrepreneurial backgrounds; (3) Founder-First Mindset; (4) Execution Speed and ability to iterate quickly; (5) Cultural Fit - coachable, responsive to feedback, capable of building strong relationships.
Geographic & Sector Focus
Geographic: California (SF Bay Area, Los Angeles), New York/Northeast, Remote-first. Sector Focus: Cybersecurity (Saveena Mandadi leads), Healthcare/Healthtech (Caroline Menkes leads), AI/ML Infrastructure (Gaurav Bhogale leads), Enterprise Software, Fintech/Payments, Creator Economy/Gaming.
Investment Process & Engagement
Sourcing through warm introductions from existing LPs and portfolio founders, proactive outreach via The Chainsmokers' network, vertical specialist sourcing, and direct founder outreach. Highly engaged post-investment through weekly founder check-ins, active recruitment support, customer/partnership introductions, and strategic advice on GTM, product, fundraising.
Competitive Positioning
Strengths: Network Leverage (The Chainsmokers + VC network), Speed, Founder Support, Brand Amplification, Domain Expertise, Cultural Fit. Disadvantages: Smaller fund size vs. mega-funds, potential founder skepticism about celebrity investors, limited geographic diversification beyond CA/Northeast.
Conclusion
Steve O'Brien represents Mantis's operational and strategic leadership. His dual role as investor and Head of Platform indicates deep involvement in fund operations, LP relations, and portfolio support infrastructure. O'Brien is best understood as both an investor focused on pre-seed/seed stage technology founders with hands-on value-add, and a strategist responsible for modernizing Mantis's fund operations and building systematic competitive advantages.