障碍期权属于奇异期权，其收益取决于标的证券的价格以及是否在规定的期限内触及特定价格，下面介绍两种类型障碍期权：

Knock-in option

A knock-in option is a latent option contract that begins to function as a normal option ("knocks in") only once a certain price level is reached before expiration. Knock-ins are a type of barrier option that are classified as either a down-and-in or an up-and-in.

触及生效期权是一种隐含的期权合约，只有在到期前达到特定价格水平才能作为期权，属于障碍期权的一种，可分为股价下跌生效的期权（down-and-in）和股价上涨生效的期权（up-and-in）。

A down-and-in option is a type of knock-in barrier option that only becomes viable when the price of the underlying security falls to a specific price level, called the barrier price. If the price does not drop to the barrier level, the option never becomes active and expires worthless. If the price reaches the barrier, the option becomes active and acts like any other option by giving the holder the right but not the obligation to exercise their call or put option at the strike price on or before the expiration date specified in the contract.

股价下跌生效的期权只有当标的证券的价格下跌至特定价格水平才存在。如果价格未降至某一障碍水平，则该期权将不会生效，到期时将一文不值。如果价格达到该障碍水平，则该期权将生效，并像其他期权一样赋予持有人在合约规定的到期日之前或当日以执行价格行使看涨期权或看跌期权的权利（并非义务）。

Up-and-in options are a type of exotic option that is often made available through specialized brokers to high-end clients in the over-the-counter (OTC) markets. The option features both a strike price and a barrier level. As the name suggests, the buyer of the option will benefit once the price of the underlying rises high enough to reach (knock-in) the designated barrier price level. Otherwise, the option will expire worthless.

股价上涨生效的期权通常由专业经济商向场外市场的高端客户提供。该期权主要包括执行价格和障碍水平。顾名思义，期权购买人只能在标的证券价格上涨得足够高能够触及指定的障碍价格水平之时获利。否则，该期权到期时将一文不值。

Knock-out option

A knock-out option is an option with a built-in mechanism to expire worthless if a specified price level in the underlying asset is reached. A knock-out option sets a cap on the level an option can reach in the holder's favor. The two types of knock-out options are up-and-out barrier options and down-and-out options.

触及失效期权的内在机制是，如果达到标的资产的特定价格，则该期权到期时将毫无价值。该期权设置了对持有人有利的水平上限。分为股价上涨失效的期权（up-and-out）和股价下跌失效的期权（down-and-out）。

An up-and-out option is a type of knock-out barrier option that ceases to exist when the price of the underlying security rises above a specific price level, called the barrier price. If the price of the underlying does not rise above the barrier level, the option acts like any other option—it gives the holder the right but not the obligation to exercise their call or put option at the strike price on or before the expiration date specified in the contract.

股价上涨失效的期权在标的证券的价格超过特定价格水平（即障碍价格）的情况下不复存在。若标的证券的价格未超过障碍水平，则该期权像其他期权一样赋予持有人在合约规定的到期日之前或当日以执行价格行使看涨期权或看跌期权的权利（并非义务）。

A down-and-out option gives the holder the right, but not the obligation, to purchase or sell an underlying asset at a predetermined strike price—if the underlying asset's price does not go below a specified barrier during the option's life. Should the underlying asset's price fall below the barrier at any point in the option's life, the option expires worthless.

就股价下跌失效的期权而言，如果标的资产的价格在整个期权期限内不低于特定的障碍价格，则期权持有人有权（并非义务）以预先确定的执行价格购买或出售标的资产。一旦标的资产的价格在期权期限内的任何时间低于特定的障碍价格，则该期权到期时将毫无价值。

参考：

Investopedia