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River Markets launch: what they're building and where to launch next

FoxPlug writes launch posts from what a startup ships and matches it to the launch communities that fit it. This page shows what River Markets is building and where it could launch next; if it is your startup, start free below.

What they're building

Prime brokerage for prediction markets

Batch
Y Combinator Spring 2026
Industry
Fintech
Team size
2
Based
San Francisco, CA, USA

Founders

rivermarkets.com ↗

See their funding details ↗

River Markets on the record

What they shipped

  • From its YC profile: 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. (source)
  • Its own site describes it as: "River Markets is the prime brokerage for prediction markets. Access professional execution across Kalshi, Polymarket, and more from a single platform." (source)

Who is behind it

  • Oscar Levy, Founder/CEO: 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. (source)
  • Antonin Parrot, Founder/CTO: 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. (source)
  • 1 open role listed on its YC jobs page when the profile was read (2026-09-05). (source)

Timeline

  1. 2026: founded, per its YC profile. (source)

Other Fintech launches on FoxPlug

  • Spectre Intelligence: We are a multi-strategy trading firm that trains AI traders.
  • Stoa: The market behind AI hardware.
  • TovenAI: AI agents for compliance at institutional trading firms

Where else to launch River Markets

  • Indie Hackers Forum ↗
    Self-promotion allowed
    Audience: IndieHackers; bootstrapped solo founders sharing revenue and behind-the-scenes
  • Hacker News (Show HN) ↗
    Self-promotion allowed, within the community's rules
    Audience: Hacker News readers; engineers, technical founders, infra-curious people
  • Product Hunt ↗
    Self-promotion allowedFree
  • Demand Curve ↗
    Self-promotion allowed, within the community's rules
    Audience: Slack community; tight-knit, pseudo-private peer group
  • No Code Founders ↗
    Self-promotion allowed, within the community's rules
    Audience: Slack community; tight-knit, pseudo-private peer group
  • OnlineGeniuses ↗
    Self-promotion allowed, within the community's rules
    Audience: Slack community; tight-knit, pseudo-private peer group
  • Product Makers ↗
    Self-promotion allowed, within the community's rules
    Audience: Slack community; tight-knit, pseudo-private peer group
  • ProductLed ↗
    Self-promotion allowed, within the community's rules
    Audience: Slack community; tight-knit, pseudo-private peer group

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Featured on FoxPlug: River Markets