Jane Street Capital is a global proprietary trading firm.^[4] It employs more than 2600^[5] people in five offices in New York, London, Hong Kong, Amsterdam, and Singapore, and trades a broad range of asset classes on more than 200 venues in 45 countries.^[6]

It is among the principal market-makers – in 2020 it traded more than $17 trillion worth of securities. It was considered to have helped keep bond exchange-traded funds (ETFs) liquid during the market turmoil in 2020.^[7]

Jane Street was co-founded by Tim Reynolds, Rob Granieri, Marc Gerstein, and Michael Jenkins.^[7][8] Reynolds, Granieri, and Jenkins were formerly traders at Susquehanna International Group.^[9] It was started in either 1999^{[1][8][10][11]} or 2000.^[4]

In 2012, Tim Reynolds stepped down from his position running the firm.^[9]

The firm ended 2020 having traded $4 trillion in global equities, $1.4 trillion in bonds, and $3.9 trillion in ETFs.^[12] During the COVID-19 pandemic, the firm saw its revenue jump 54% to a record of $10.6 billion during the year ended in March 2021.^[13]

As of 2021, its trading capital was about $15bn. As well as high-frequency trading, it in some cases maintained positions for hours, even days or sometimes weeks, which is essential for ETFs that track less-traded markets. On any given day, it was holding about $50bn of securities. It is an authorised participant^[14] in 2,600 ETFs and lead market-maker on 506 ETFs, and plays an important role in maintaining ETF liquidity.^[15]

In 2023, the company generated $10.6bn in net trading revenue with adjusted earnings of $7.4bn. It released these numbers as part of a debt deal which aimed to expand the amount of cash on Jane Street's balance sheet from $4.3bn to $5.6bn.^[16]

Almost all of its software is written in the OCaml programming language.^{[17][15][18][19][20]}

The company is informally led by a group of 30 or 40 senior executives.

The firm's culture includes a focus on the risks of improbable but catastrophic crashes. In addition to hedging at trading desk level, Jane Street at company level spends $50m-$75m a year on put options.^[15]

In April 2024, the firm brought a lawsuit against Millennium Management alleging that Millennium stole its trading strategy through engaging two of its former traders, Douglas Schadewald and Daniel Spottiswood.^[21] The firm claimed the strategy, which traded options in NSE/BSE India, earned about $1 billion in 2023.^[22]

• Sam Bankman-Fried^[23] and Caroline Ellison,^[24] recipients of misappropriated FTX customer funds, were once employed by the company.^[25]
• Brett Harrison.