1. A fucking retard.
2. One who lacks the social graces given to even the most rudimentary of mossy vegitation.
3. One who has lost all sense of reality whilst performing even the most menial of tasks.
The owner of the 3X ETF FAS (Direxion Financials Bull 3X ETF). The term denotes someone who goes "long" FAS, i.e. buys the equity. Tard is common in stock lingo for anyone who has a long position.