A rogue trader is an authorised employee making unauthorised trades on behalf of their employer. It is most often applicable to financial trading, and as such is a term used to describe persons - professional trader

Trader (finance)

A trader is someone in finance who buys and sells financial instruments such as stocks, bonds, commodities and derivatives. A broker who simply fills buy or sell orders is not a trader, as they are merely executing instructions given to them. According to the Wall Street Journal in 2004, a managing...

s - making unapproved financial transactions.

This activity is in the grey area between civil and criminal illegality for the reason that the perpetrator is a legitimate employee of a company or institution, yet enters into transactions on behalf of their employer without permission.

One famous rogue trader is Nick Leeson

Nick Leeson

Nicholas "Nick" Leeson is a former derivatives broker whose fraudulent, unauthorized speculative trading caused the collapse of Barings Bank, the United Kingdom's oldest investment bank, for which he was sent to prison...

, whose losses were sufficient to bankrupt Barings Bank

Barings Bank

Barings Bank was the oldest merchant bank in London until its collapse in 1995 after one of the bank's employees, Nick Leeson, lost £827 million due to speculative investing, primarily in futures contracts, at the bank's Singapore office.-History:-1762–1890:Barings Bank was founded in 1762 as the...

 in 1995 following his ill-advised and unauthorized investments in index futures. Through a combination of poor judgement on his part, lack of oversight by management, a naïve regulatory environment and unfortunate outside events like the Kobe earthquake

Great Hanshin earthquake

The Great Hanshin earthquake, or Kobe earthquake, was an earthquake that occurred on Tuesday, January 17, 1995, at 05:46 JST in the southern part of Hyōgo Prefecture, Japan. It measured 6.8 on the moment magnitude scale , and Mj7.3 on JMA magnitude scale. The tremors lasted for approximately 20...

, Leeson incurred a $1.3 billion

1000000000 (number)

1,000,000,000 is the natural number following 999,999,999 and preceding 1,000,000,001.In scientific notation, it is written as 109....

 loss that bankrupted the centuries-old financial institution.

Table of largest rogue trader losses

Name	Date(s)	Loss	Institution	Market activity	Sentence
Nick Leeson Nick Leeson Nicholas "Nick" Leeson is a former derivatives broker whose fraudulent, unauthorized speculative trading caused the collapse of Barings Bank, the United Kingdom's oldest investment bank, for which he was sent to prison...	1995	5 £827 million leading to bank failure	Barings Bank Barings Bank Barings Bank was the oldest merchant bank in London until its collapse in 1995 after one of the bank's employees, Nick Leeson, lost £827 million due to speculative investing, primarily in futures contracts, at the bank's Singapore office.-History:-1762–1890:Barings Bank was founded in 1762 as the...	Nikkei index Nikkei 225 The , more commonly called the Nikkei, the Nikkei index, or the Nikkei Stock Average , is a stock market index for the Tokyo Stock Exchange . It has been calculated daily by the Nihon Keizai Shimbun newspaper since 1950. It is a price-weighted average , and the components are reviewed once a year...  futures Futures contract In finance, a futures contract is a standardized contract between two parties to exchange a specified asset of standardized quantity and quality for a price agreed today with delivery occurring at a specified future date, the delivery date. The contracts are traded on a futures exchange...	6.5 years jail
Toshihide Iguchi Toshihide Iguchi is a former Japanese government bond trader at Daiwa Bank responsible for $1.1 billion in losses involving 30,000 unauthorized trades over a period of 11 years beginning in 1984.- Biography :...	1995	4 $1.1 billion	Resona Holdings	U.S. Treasury bonds	4 years jail
Yasuo Hamanaka Yasuo Hamanaka is a man who formerly was the chief copper trader at Sumitomo Corporation, one of the largest trading companies in Japan, and was also known as "Mr. Copper" because of his aggressive trading style and "Mr...	1996	6 $2.6 billion	Sumitomo Corporation Sumitomo Corporation Sumitomo Corporation is one of the largest worldwide trading company , and is a diversified corporation. Sumitomo is headquartered in the Harumi Island Triton Square Office Tower Y in Chūō, Tokyo, Japan...	copper	8 years jail
John Rusnak John Rusnak John Rusnak is a former currency trader at Allfirst bank, then part of AIB Group, in Baltimore, MD, United States. On January 17, 2003 he was sentenced to 7½ years in prison for hiding US$691 million in losses at the bank, after bad bets snowballed in one of the largest ever cases of bank fraud...	2002	3 $691 million	Allied Irish Banks Allied Irish Banks Allied Irish Banks p.l.c. is a major commercial bank based in Ireland.AIB is one of the so called "big four" commercial banks in the state. The bank has one of the largest branch networks in Ireland; only Bank of Ireland fully rivals it. AIB offers a full range of personal and corporate banking...	foreign exchange Foreign exchange market The foreign exchange market is a global, worldwide decentralized financial market for trading currencies. Financial centers around the world function as anchors of trading between a wide range of different types of buyers and sellers around the clock, with the exception of weekends...  options Option (finance) In finance, an option is a derivative financial instrument that specifies a contract between two parties for a future transaction on an asset at a reference price. The buyer of the option gains the right, but not the obligation, to engage in that transaction, while the seller incurs the...	7.5 years jail
Gianni Gray, David Bullen, Vince Ficarra, Luke Duffy	2003 Oct - 2004 Jan	1 AU$360 million	National Australia Bank National Australia Bank National Australia Bank is one of the four largest financial institutions in Australia in terms of market capitalisation and customers. NAB is ranked 17th largest bank in the world measured by market capitalisation...	foreign exchange Foreign exchange market The foreign exchange market is a global, worldwide decentralized financial market for trading currencies. Financial centers around the world function as anchors of trading between a wide range of different types of buyers and sellers around the clock, with the exception of weekends...  options Option (finance) In finance, an option is a derivative financial instrument that specifies a contract between two parties for a future transaction on an asset at a reference price. The buyer of the option gains the right, but not the obligation, to engage in that transaction, while the seller incurs the...	16 months jail, 3 years and 8 months jail, 2 years and 4 months jail, 2 years 5 months jail
Chen Jiulin Chen Jiulin Chen Jiulin Corporation Ltd . During his leadership CAO’s net asset worth increased from US$176,000 to US$150,000,000, an increase of 85,200%. The market cap rose to 1.1 billion US dollars, which was 5,022 times the original value...	2005	2 $550 million	China Aviation Oil	jet fuel futures Futures contract In finance, a futures contract is a standardized contract between two parties to exchange a specified asset of standardized quantity and quality for a price agreed today with delivery occurring at a specified future date, the delivery date. The contracts are traded on a futures exchange...	4 years and 3 months jail
Jérôme Kerviel Jérôme Kerviel Jérôme Kerviel is a French trader who has a pending appeal of his conviction in the January 2008 Société Générale trading loss incident for breach of trust, forgery and unauthorized use of the bank's computers, resulting in losses valued at €4.9 billion.Société Générale characterizes Kerviel...	2006–2008	7 €4.9 billion	Société Générale Société Générale Société Générale S.A. is a large European Bank and a major Financial Services company that has a substantial global presence. Its registered office is on Boulevard Haussmann in the 9th arrondissement of Paris, while its head office is in the Tours Société Générale in the business district of La...	European stock index futures Futures contract In finance, a futures contract is a standardized contract between two parties to exchange a specified asset of standardized quantity and quality for a price agreed today with delivery occurring at a specified future date, the delivery date. The contracts are traded on a futures exchange...	5 years prison of which 2 years are suspended - may still appeal ruling
Boris Picano-Nacci	2008 Oct	7 €751 million	Groupe Caisse d'Epargne Groupe Caisse d'Epargne Groupe Caisse d'Epargne is a French semi-cooperative banking group, founded in 1818, with around 4700 branches in the country. The group is active in retail and private banking, as well as holding a significant stake in the publicly traded investment bank Natixis.-Operations:The group's most...	Equity Derivatives	investigation in progress
Kweku Adoboli	2011	7 $2.3 billion	UBS	S&P 500, DAX, and EuroStoxx index futures	investigation in progress