Justin Mateen is a legendary tech investor and the sole GP of JAM Fund. He often invests personal capital first, then backs the winners at every stage with JAM Fund and personal capital side by side. Fund I was $100M, and Fund II was $329M, and including his personal investments alongside the fund, he has deployed significantly more capital. He is known to back founders with a chip on their shoulders and is often a contrarian investor. His track record includes Kalshi (entered at $10M), Deel (entered at $15M), Curative Health (entered at $3M), Whop (entered at $3M), and Slash (entered at $7M). He has also backed Speak (entered at $10M), Varda Space Industries (entered at $20M pre-money), Stoke Space (entered at $20M), Radiant Nuclear (entered at $20M), and Hadrian (entered at $15M), spanning frontier categories like space manufacturing, nuclear energy, and AI infrastructure alongside consumer and fintech. He backed SpaceX (entered at $20B in 2017) and The Boring Company (entered at $900M in 2019). He previously co-founded Tinder, where he served as Chief Marketing Officer. He has a significant personal portfolio of real estate spanning industrial, retail, office, and hotel.