Jane Street

Jane Street operates as a principal market-maker — it continuously quotes buy and sell prices on exchanges and trading venues worldwide, earning the bid-ask spread. The firm takes no client money and runs no asset-management business. Revenue is exclusively from proprietary trading across equities, ETFs, bonds, currencies, options, and crypto.

Brad Katsuyama, a former Global Head of Trading at Jane Street, left the firm in 2012 after growing frustrated with latency advantages sold by exchanges to high-frequency traders. He co-founded IEX — the Investors' Exchange — and a related software company, which were the subject of Michael Lewis's 2014 book 'Flash Boys.' Jane Street itself was portrayed as one of the sophisticated market-makers whose technology IEX sought to neutralize.

No. Jane Street trades exclusively proprietary capital belonging to the firm's partners and employees. It does not solicit, accept, or manage outside investor funds, which distinguishes it from hedge funds, asset managers, and family offices.

Jane Street is the most significant corporate user and steward of OCaml, a functional programming language. The firm built its entire trading infrastructure on OCaml, sponsors academic conferences, employs core compiler developers, and open-sources substantial libraries. This gives the firm an unusual talent pipeline from computer science departments and creates a technical culture barrier that competitors find difficult to replicate.

Jane Street is widely reported to handle roughly 12–14% of all US-listed ETF trading volume, making it the largest ETF market-maker globally. In notional terms, the firm trades over $17 billion in ETFs daily, according to a Bloomberg analysis in 2024. It is an authorized participant for most major ETF issuers.