Positive Sum Research
Investment Thesis
Positive Sum is a Greenwich, Connecticut venture firm founded in 2020 by Patrick O'Shaughnessy, the host of the Invest Like the Best podcast and founder of the Colossus media network. Its homepage states one line of thesis: "We back founders pursuing their life's work." The firm is founder-centric rather than sector-centric. It does not publish a sector list, an anti-thesis or a check-size policy. Its portfolio shows what the thesis means in practice: ambitious, often technical founders building category-defining companies in AI, energy, healthcare, financial software and consumer products, backed early and then followed through later rounds.
Stage Focus
PitchBook classes the firm as early-stage venture and lists it as actively seeking new investments. The actual record is wider than that label. The firm took part in early rounds, for example a seed in Dirac in August 2025 and an early-stage round in Inheritance in May 2026. It also keeps writing checks into later rounds of winners: Rogo's Series D in April 2026, Cognition's Series D in May 2026 and Series E in September 2026, and Etched in August 2026. The pattern is early entry with heavy follow-on in companies that work. Stage preferences are therefore Seed, Series A and growth follow-ons.
Check Size
The firm publishes no range. The only disclosed figure found is a $20M investment in Tegus in 2022 (PR Newswire, September 2022), which is a large check for a firm of this type. Early checks are not disclosed. No check size range is stored for this reason.
Lead Tendency
Both. It was named as a co-lead of Rogo's $160M Series D alongside Kleiner Perkins (April 2026) and led the $20M Tegus round. It also appears in lists of participants (Rogo Series C, Base Power Series C, Cognition Series E, where the round was led by Andreessen Horowitz and Accel).
Recent Activity
PitchBook shows 61 investments, 38 portfolio companies and 7 exits as of October 2026. Recent entries include Cognition (September 2026 Series E, at a $48B valuation, and May 2026 Series D), Etched (August 2026), Neko Health (July 2026), Speakeasy (June 2026), Augusta Labs (June 2026), Tractive (May 2026), Witan Labs (May 2026), Inheritance (May 2026) and Rogo (April 2026). Exits include the Bending Spoons IPO (July 2026), Tegus (acquired by AlphaSense, 2024), Passthrough and Careswitch. The firm files Form D for Positive Sum Capital IV, LP in August 2026, which indicates a fourth fund is raising or recently closed; size is not public in the sources reviewed. Fund status: actively deploying.
Portfolio Highlights
The website lists 28 highlights: Etched, Cognition, Base Power, Imprint, Modal, Rogo, Neko Health, Physical Intelligence, Vanta, Bending Spoons, Skyryse, Arc, Alpaca, January, Ridgeline, Tegus, Prefect, Canopy, Blues, Invert, Fortell, Inheritance, Entrepreneurs First, Arcana, Eight Sleep, ID.me, Casa and Retro. The mix covers AI chips and coding agents, home batteries, consumer fintech, preventive health, robotics foundation models, compliance, aviation software and consumer hardware.
Team
Patrick O'Shaughnessy is the founder and CEO. Silicon Valley Investclub lists Alison Davis Riddell, Jeremy Stern and Brie Wolfson as partners; Alison and Jeremy also work on Colossus editorial (Editor-in-Chief and Managing Editor). The remaining names on the team page (Dom Cooke, Joe Parker, Donald Lee-Brown, Terran Mott, Eric Jasinski, Joe Berg, Gabi Marques, Avidan Rudansky, Julia Hitchins) are described on the Colossus about page as creative, research, engineering, operations and podcast staff, so they are not stored as investors. LinkedIn also names Sam Cates as a co-lead of the firm; he is not on the team page.
Decision Process
Not published. The firm is a small partnership led by a single founder, so decisions most likely run through Patrick and the partners rather than a formal committee. Treat as partnership, low confidence.
Founder Preferences
Founders working on a long-term mission ("life's work"), strong technical or product conviction, often in capital-intensive or hard problems (chips, batteries, aviation). The Colossus media network and podcast give the firm a distribution and brand advantage with such founders, and its content is a typical route in for founder conversations. No public stance on warm intros; the firm is widely reachable through Patrick's network.
Geographic Focus
Predominantly US (Austin, SF Bay Area, New York) with some European exposure: Neko Health (Sweden), Bending Spoons (Italy), Tractive (Austria).