A turbo warrant (or callable bull/bear contract) is a kind of stock option.
It is similar to a vanilla contract, but with two additional features: It has a low vega, meaning that the option price is much less affected by the implied volatility of the stock market, and it is highly geared due to the possibility of knockout.
A turbo will have a positive value at expiry when the spot settle above the strike AND the spot has never fallen below the strike during the life of the option (if it had done so the option would have crossed the barrier (=strike) and would have become worthless).
[2] In Germany, buying and selling turbo warrants constitute 50% of all speculative derivatives trading.
Turbo warrants were introduced to the Hong Kong Stock Exchange (HKEx) in 2006 in the name of Callable Bullish/Bearish Contracts (CBBC).