Justin Mateen
About Justin Mateen
Justin Mateen co-founded Tinder in 2012 and served as its chief marketing officer until 2014. He graduated from USC Marshall School of Business. Before Tinder he started CoverCanvas, and he was named to the Forbes 30 Under 30 consumer technology list.
After leaving Tinder he became an early-stage investor and founded JAM Fund, where he is the founder and managing partner. He also holds Los Angeles real estate and hospitality investments, which are separate from his startup investing. Crunchbase lists him in board and advisor roles, including Koinz and Home Chef.
Mateen describes himself on X as a seed investor in Curative, Deel, Kalshi, Slash, Speak and Whop. Crunchbase notes that Business Insider ranked him first on its list of top US seed investors in 2021 and 2022. In a 2025 post he said SpaceX was his first major investment after he gained liquidity, made in 2017.
PitchBook lists 129 investments, 69 portfolio companies and 50 exits for him as an individual angel. It is a third-party tally and may not match his own records. Earlier press coverage names FabFitFun, Jobr and Home Chef as early-stage investments.
Subquadratic raised a $29M seed round in May 2026, and Mateen is named among its investors. TAMradar reports that Javier Villamizar also participated. The Miami-based company builds sub-quadratic large language models. Its first model, SubQ, has a 12M-token context window. The funding is meant to expand its private beta for API, coding and search products. TAMradar also reports a $500M post-money valuation, which the company has not confirmed in the sources reviewed.
We found no other AI-specific investments with confirmed dates.
He invests at pre-seed, seed and Series A, according to the VC Sheet directory. It lists consumer, fintech, health, CPG and transportation as sectors. His portfolio also includes space and frontier-technology companies such as Varda Space Industries and ABL Space Systems. VC Sheet describes him as investing personally first, then backing winners through JAM Fund.
JAM Fund raised nearly $102M for its first fund, and the Los Angeles Business Journal reported $247.5M raised for JAM Fund 2 in an SEC filing. VC Sheet lists a check range of $500K to $20M. That range comes from the directory, not from a statement by Mateen. He told the L.A. Times he is a contrarian who takes a long view and holds through cycles. He has not published a founder checklist or an AI-specific thesis that we found.
- Subquadratic: sub-quadratic LLM developer, $29M seed in May 2026
- Kalshi: regulated event-contract prediction market, listed seed investment
- Deel: global payroll and hiring platform, listed seed investment
- Curative: health company, listed seed investment
- Whop: online marketplace for digital products, listed seed investment
- Slash: business banking and payments platform, listed seed investment
- Speak: language-learning app, listed seed investment
- Varda Space Industries: in-space manufacturing, JAM Fund investment
- ABL Space Systems: launch vehicle maker, JAM Fund investment
- SpaceX: invested in 2017
- crunchbase.com/person/justin-mateen
- x.com/justinmateen
- vcsheet.com/who/justin-mateen
- labusinessjournal.com/finance/justin-mateen-venture-capital-fund-bel-a
- labusinessjournal.com/news/justin-mateen
- tamradar.com/funding-rounds/subquadratic-seed-29m
- pitchbook.com/profiles/investor/106382-62
- therealdeal.com/la/2025/06/27/tinder-co-founder-grabs-hollywood-galaxy
Investing activity
Justin Mateen appears in 1 AI deal tracked by the Lounge deals desk, rounds totalling $29M. The rounds are mostly Seed, with a median round size of $29M. The most recent is Subquadratic (Seed, $29M, May 2026).
Justin Mateen most often invests alongside Ullas Naik, Streamlined, JAM Fund and Brex, and the companies they back on Lounge are mostly in AI.
Deals
Frequently asked questions about Justin Mateen
Who is Justin Mateen?
He is a co-founder of Tinder, where he was chief marketing officer from 2012 to 2014. He now runs JAM Fund and invests in early-stage companies.
Has Justin Mateen invested in AI companies?
Yes. He is named among the investors in Subquadratic's $29M seed round in May 2026. Subquadratic builds sub-quadratic large language models.
What stage does Justin Mateen invest in?
VC Sheet lists pre-seed, seed and Series A. His own X bio describes him as a seed investor.
What check size does Justin Mateen write?
He has not stated a check size publicly. VC Sheet lists a range of $500K to $20M for his fund, and that range is unconfirmed by him.
How big is JAM Fund?
The Los Angeles Business Journal reported that JAM Fund raised nearly $102M. It also reported $247.5M raised for JAM Fund 2, based on an SEC filing.
How can founders contact Justin Mateen?
He is active on X at @justinmateen and lists a personal site at justinmateen.com. No public pitch process or submission form turned up.
Is Justin Mateen an angel investor?
Yes. Justin Mateen invests personally as an angel.
What AI companies has Justin Mateen invested in?
Justin Mateen's AI investments include Subquadratic. The 1 round on Lounge are listed on this page with amounts, dates and co-investors.
What stage does Justin Mateen invest at?
In the rounds tracked on Lounge, Justin Mateen has invested at Seed, with a median round of $29M.
Who does Justin Mateen co-invest with?
Justin Mateen's most frequent co-investors on Lounge are Ullas Naik (1 deal), Streamlined (1 deal), JAM Fund (1 deal), Brex (1 deal) and OpenAI (1 deal).