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River Markets

River Markets

Prime brokerage for prediction markets

Spring 2026ActiveFintechTradingSan Francisco, CA, USA
Company
https://www.rivermarkets.com
River Markets is the prime brokerage for prediction markets. We aggregate every major event-contract venue into one account, giving professional traders best execution, portfolio and order management systems, and a unified API.

Verdict

High Signal
Market Opportunity
Prediction markets have exploded post-Polymarket/Kalshi, with institutional and professional traders increasingly active. A prime brokerage layer targeting professional traders is a clear B2B fintech ICP with obvious monetization via commissions, margin lending, and API fees. The market is real, growing fast, and currently underserved at the infrastructure layer.
High Signal
Founder Signal
Oscar Levy has direct quant experience at BlackRock managing models trading $6B and at Sandbar Asset Management ($2B AUM hedge fund) — directly relevant financial infrastructure pedigree. Antonin Parrot is an HFT options market maker quant, bringing execution/latency expertise critical for a prime brokerage. This is an unusually well-matched technical team for this exact problem — both have institutional trading credentials.
Medium Signal
Competition
No direct competitor data found, but Kalshi, Polymarket, and traditional prime brokers (who ignore prediction markets) are adjacent. The aggregation/PMS layer is genuinely novel — no one appears to be doing unified prime brokerage across prediction market venues yet. However, the venues themselves could build this, and it's early enough that the competitive moat is unproven.
Low Signal
Product
No live demo, no API docs, no customer logos, no pricing page visible. Description is conceptual — 'aggregate every major event-contract venue into one account' sounds compelling but there's zero evidence of a working product, customers, or revenue. No press coverage whatsoever.
OverallB Tier

Exceptionally well-credentialed founders for exactly this problem — a BlackRock quant + HFT market maker building prime brokerage infrastructure for prediction markets is a rare founder-market fit. The market timing is strong given prediction market growth and the lack of institutional-grade tooling. However, there is zero evidence of a working product, customers, or any traction, which makes this pre-product vaporware right now. The core risk is that this is infrastructure for a market that may not yet have enough professional volume to sustain a standalone prime broker, and the venues themselves (Kalshi, Polymarket) are natural acquirers who could build this layer internally. Worth watching closely but needs to show product and early customers to upgrade.

Active Founders

Oscar Levy
Oscar Levy
Co-Founder

Co-Founder at River Markets. Previously quant at BlackRock managing models trading $6B, Sandbar Asset Management ($2B AUM hedge fund). MA Financial Engineering from UC Berkeley.

Antonin Parrot
Antonin Parrot
Founder

Co-founder of River Markets, the prime broker for prediction markets. I have a background in engineering and CS, and I've been working as a quant at a high frequency option market making trading shop.

River Markets
River Markets
TierB Tier
BatchSpring 2026
Team Size2
StatusActive
LocationSan Francisco, CA, USA
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