中文摘要：

泡沫一般是指资产以高于其价值的价格进行交易。但是，通常情况下我们很难观察到资产（例如房屋）的价值，资产是否存在泡沫（例如中国当前的房地产市场）也就很难达成共识。权证作为一类特殊的资产，其价值相对比较容易确定，成熟的理论模型、权证的价值上限和标的股票的涨跌幅限制为我们确定权证的价值提供了有力的工具．进而使我们更容易发现泡沫的存在。本文对认购权证的研究发现：①认购权证的交易价格显著高于其理论价值，即使不使用理论模型也可以发现权证在其理论价值之上交易：②与被认为存在严重泡沫的认沽权证相比，认购权证的泡沫更大，表现为价格偏离程度更高、换手率更高；③卖空限制和投资者的异质信念是权证泡沫形成的主要来源．极低的交易费用、T＋O交易制度、高涨跌幅和高波动率给权证交易者带来的刺激促使泡沫的存续与发展。对于中国证券市场而言，上一次权证市场虽然存在明显泡沫并存在争议，但金融市场需要权证等金融产品来进行风险管理和促进价格发现，权证市场需要在进行必要制度建设和广泛的投资者教育基础上尽快重启。

英文摘要：

Asset price bubbles are defined as the asset price exceeds the asset＇ fundamental value. The difficulty in measuring asset fundamentals complicates the confirmations of existence of bubbles, such as the controversial topic whether current Chinese real estate market is experiencing bubbles. However, the fundamental value of warrants is easily measured compared with that of other assets. The upper bound of warrants＇ fundamental value, which can be determined by the price of underlying stocks, the price-change limit of its underlying stocks, and the Black-Scholes model, gives us the useful tools to determine the existence of bubbles. Firstly, the market prices of call warrants significantly deviated from the theoretical prices, which whether were implied by Black- Scholes model or model free. Secondly, the call warrants＇ bubble is higher the put warrants＇. Lastly, the Short- sales constraints and heterogeneous beliefs in driving bubbles are a key driver of warrant bubbles. Low transfer fees, ＂T ＋ 0＂ rule, wider daily price change limit and high return volatility make warrant trading like lottery playing, which gives warrant trades entertainment. The warrants market was closed for its bubble. The warrants market should be re-opened soon for investors can use it to hedge or mitigate the risk. Before it, investor＇s education and effective regulation of the financial market are needed.