One who doesn't do what's expected

• An investor who deliberately decides to go against the prevailing wisdom of other investors
• Person who doesn't jump on the bandwagon

Wikipedia Word definitions in Wikipedia
A contrarian is a person who takes up a contrary position, especially a position that is opposed to that of the majority, regardless of how unpopular it may be.

WordNet Word definitions in WordNet
n. an investor who deliberately decides to go against the prevailing wisdom of other investors

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
contrarian \con*tra"ri*an\, n. [see contrarian , a..] a person who habitually takes a view opposite to that held by the majority; as, the contrarians in the stock market prefer to sell when most analysts advise us to buy.

Wiktionary Word definitions in Wiktionary
n. 1 a person who expresses a contradicting viewpoint, especially one who denounces the majority persuasion 2 (context finance English) a financial investor who tends to have an opinion of market trends at variance with most others

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1963, from contrary + -ian .\n\nTo be in opposition is not to be a nihilist. And there is no decent or charted way of making a living at it. It is something you are, and not something you do. [Christopher Hitchens, "Letters to a Young Contrarian," 2001]