Financial Controller

Ostium is on a simple mission: make it possible for anyone with a digital wallet to trade stocks, commodities, currencies, and crypto with full transparency. No brokers, no freezes, no hidden spreads. We’re replacing the opaque, offshore brokerage model with a transparent, permissionless trading stack built onchain. Every trade, deposit, and withdrawal is verifiable through open, auditable code. We’ve raised $27.9M+ from General Catalyst, Jump, LocalGlobe, Susquehanna (SIG), GSR, Alliance DAO, Soma Capital, Balaji Srinivasan, Meltem Demirors, and others. ROLE Remote / Full-Time ABOUT OSTIUM Ostium is building the neo-broker for the onchain world, one place to trade the world's markets, with the depth and execution of an institutional desk and the openness of a public blockchain. Global markets still run on infrastructure built decades ago: opaque brokers, black-box pricing, permissioned and geography-gated access. Meanwhile, a new kind of trader, global, self-directed, cross-asset, stablecoin-native, has outgrown all of it. That trader is who we're building for. Real-world assets are moving onchain fast, and there's more than one way to get there. Much of the industry is working to rebuild that liquidity onchain from the ground up. We took a different view: the world's deepest markets, the venues that price global oil, gold, currencies, and equities, already hold the liquidity traders want. What's broken is access to it. So we built the genuinely hard part: the legal, operational, and technical infrastructure to connect directly into those markets and route their liquidity onchain, to anyone with a wallet. Prime-broker-grade access, in the hands of the individual trader, with every spread, liquidation, and dollar of collateral verifiable onchain. And it's working. Traders now run eight-figure positions through Ostium, including the largest onchain oil trade ever executed, because nothing else onchain can hold that size. We're defining a new category, and we're already ahead in it. WHY NOW Perpetuals just went mainstream. US regulators have opened the door to digital commodity perps, the products are in every major outlet, and real-world assets are moving onchain faster than anyone predicted. The winds have never been more at our back. The demand we built for is arriving in force, and the window to define this category is open now. TRACTION We've raised $27.9M+ from General Catalyst, Jump, Susquehanna (SIG), Wintermute, and angels including Balaji Srinivasan and Meltem Demirors. Our highest-retention traders are whales who stay on product merit alone, not because of incentives, often requesting size in a way that verges on OTC. Record block trades run through us because the liquidity model is built for exactly that. HOW WE WORK We're a 30-person team across New York, Miami, and Porto, Portugal, and every time zone in between. Our founding team includes Harvard and Bridgewater alumni, along with medalists in International Olympiads (Physics, Biology). We're here to win, which means shipping fast and staying obsessed with what our traders actually need. We're a meritocracy, not a democracy. We debate hard, but once a call is made we disagree and commit, then row together. We also believe being AI-native is one of the only ways to scale properly. Our best operators and engineers know how to leverage AI without ever surrendering their judgment to it. Lead and hone your own intuition, but leverage the machine to scale your efforts. We know the cost of the old way firsthand. We started Ostium in a hacker house at Harvard after an offshore broker froze our accounts and kept our deposits. If you can't verify it, you don't own it. That conviction is now infrastructure. Building the neo-broker layer takes range: markets, pricing, risk, engineering, design, and operations. If that's you, there's no second best. ROLE OVERVIEW As Ostium's Controller, you will direct our accounting operations and implement institutional-grade financial fram…