# James R. Stewart

> James R. Stewart is a builder: a founder and product manager who has spent his career building financial products at the edge of finance and new technology. He is the founder of Belief Systems, the measurement layer for prediction markets, and a crypto product manager at SoFi. He previously built products at Eigen Labs, StellarFi, Genesis, and BlackRock.

Not to be confused with the actor James Stewart (1908–1997) or other people named James Stewart.

## Facts

- Name: James R. Stewart (also written James Stewart)
- Role: Founder & Product Manager
- Location: Remote, USA
- Website: https://jamesstew.art
- Contact: jamesrstew@gmail.com
- LinkedIn: https://www.linkedin.com/in/james-r-stewart/
- GitHub: https://github.com/jamesrstew

## Experience

- Founder, Belief Systems (2025–present): The measurement layer for prediction markets: independent benchmarks, forward volatility, and market grades.
- Crypto Product Manager, SoFi (2025–present): Leads crypto lending, earn, and transfers.
- Senior Product Manager, Eigen Labs (2024–2025): Led staking and developer experience.
- Director of Product Management, StellarFi (2023–2024): Early product hire; led a major B2B2C pivot.
- Lead Product Manager, Genesis (2021–2023): Helped scale Genesis into the largest crypto lender of all time, with $131 billion in loan originations.
- Product Analyst, then Product Manager on Aladdin, BlackRock (2016–2021): Built a 0-to-1 bond trading tool for institutional investors and re-architected Mortgage Browser.
- Co-Founder, Cairn Media (2015–2016): Built white-label mobile apps for zoos and museums, launching with the Reid Park Zoo in Tucson.

## Projects

- [Belief Systems](https://beliefsystems.xyz): The measurement layer for prediction markets.
- [Toastery Roastery](https://toasteryroastery.com): Micro-roasted coffee, made to order. The anti-coffee-subscription subscription.
- [Birthday Bread](https://birthdaybread.com): Text "bread" and a loaf shows up for someone you love. I keep no profit.
- [James St. Journal](https://www.jamesstjournal.com/): A daily paper written and edited by Claude. It ran for 147 editions.
- [Splitluride](https://jamesstew.art/telluride-splitwise/): Expense splitting for a ski trip. Shred now, settle later.
- [Cumulus](https://cumulusbreathing.com): A breathwork app.
- [James Stewart Club](https://james-stewart.club): A club for people named James Stewart.

## Research

- [Benchmark Indices of Market-Implied Event Probabilities: Construction, Valuation, and Governance of the Belief Index Family](https://ssrn.com/abstract=7089198) (SSRN, 2026-07), by James R. Stewart
- [Forward Belief Volatility in Prediction Markets: A Budget-Anchored Term Structure](https://ssrn.com/abstract=7220678) (SSRN, 2026-08), by James R. Stewart

## Press

- [Garage upstart turns Polymarket bets into benchmarks](https://www.risk.net/markets/7963857/garage-upstart-turns-polymarket-bets-into-benchmarks) (Risk.net, 2026-07-17), about Belief Systems

## Notes

Essays by James R. Stewart, newest first. Each link is a clean Markdown version of the page.

- [Winning Team, Losing Team](https://jamesstew.art/notes/winning-team-losing-team/index.md) (2026-09-11): On moving between winning and losing companies, and why it's so hard to tell how good you are while you're on either.
- [Big Company, Small Company](https://jamesstew.art/notes/big-company-small-company/index.md) (2025-11-10): Reflections on the differences between working at startups and big companies, and what each environment teaches you.
- [Low / No Tech](https://jamesstew.art/notes/low-no-tech/index.md) (2025-09-08): Reflections on technology overload and the enduring value of simple, low-tech inventions that solve fundamental problems.
- [Self Inquiry](https://jamesstew.art/notes/self-inquiry/index.md) (2025-09-08): Practices, prompts, and resources for radical self-inquiry: journaling, fear-setting, books, and talks.
- [New Dad](https://jamesstew.art/notes/new-dad/index.md) (2025-07-28): On May 24, 2025 at 4:30 am, Taylor and I welcomed our first son, Devereux Benjamin Stewart. We call him Dex.
- [I Love LMNT. LMNT Is a Scam.](https://jamesstew.art/notes/hydration/index.md) (2024-10-20): My complicated relationship with LMNT, and how I made my own electrolyte mix at home.
- [Recipes](https://jamesstew.art/notes/recipes/index.md) (2024-10-20): A collection of favorite recipes: the best pancakes and sourdough pita bread.
- [Experimenting with AI](https://jamesstew.art/notes/ai/index.md) (2024-02-24): Exploring AI applications in fintech: using ChatGPT and custom GPTs to generate personalized credit report insights.
- [Principles](https://jamesstew.art/notes/principles/index.md) (2024-01-27): Truths about life, working effectively in the workplace, and building products.
- [Good Eggs](https://jamesstew.art/notes/good-eggs/index.md) (2024-01-21): I love good eggs. A slightly satirical formula for gauging eggcellence, and a ranking of the eggs I could find.
- [Advice for Aspiring PMs](https://jamesstew.art/notes/advice-for-aspiring-pms/index.md) (2023-05-12): Quick advice if you want to break into product management.
- [New Products](https://jamesstew.art/notes/new-products/index.md) (2023-02-23): Thoughts on launching new products: my product development process, from the first idea to the final product.

## Optional

- [Full text of every note](https://jamesstew.art/llms-full.txt)
- [Atom feed](https://jamesstew.art/feed.xml)