[Sell Beta as Alpha]
以上两个模型的成功运用表明了对冲基金提供的alpha中大部分来自于已知的风险因子敞口,而真正的超额市场回报相当有限。所以他们是在把beta当成alpha在推销(sell beta as alpha)。它们能取得回报的一个重要原因并不是因为它们能提供下行风险的对冲(protection on downside risk),恰恰相反,而是因为它们在市场下行的时候回报足够糟糕,也就是说它们对尾部风险(tail risk)的敞口很大(见[9],[10])。
这符合因子投资的特性,即人们承担的(系统性)风险越大(尤其在状态‘坏’时),作为补偿的因子风险溢价(factor risk premium)也越大(尤其在状态‘好’时)。所以,对冲基金与其他资产无异。当市场上行时,投资组合中的对冲基金类资产会有不同收益,起到分散投资的作用(diversification),但当市场下行时,各类对冲基金都会遭受损失。为了更好地解释对冲基金回报,人们在上述七因子模型的基础上又加了两个尾部风险因子:标准普尔500虚值看跌期权回报(OTM put option)和标准普尔500虚值与平价看跌期权回报差(return spread between OTM and ATM put option)。
[参考文献]
[1] 解密世界最赚钱耶鲁基金是怎样进行资产配置的(https://bbs.pinggu.org/thread-3128561-1-1.html)
[2] 【推荐】一文读懂美国对冲基金行业(https://bbs.pinggu.org/thread-3132585-1-1.html)
[3] 对冲基金扫盲帖(https://bbs.pinggu.org/thread-3116465-1-1.html)
[4] Lars Jaegar, "Alternative Beta Strategies and Hedge Fund Replication", Wiley Finance, 2009
[5] 对于目前流行的量化投资与smart beta的一些看法(https://bbs.pinggu.org/thread-3151691-1-1.html)
[6] Hasanhodzic and Lo, “Can Hedge-fund Returns be Replicated?: The Linear Case”, Journal of Investment Management, Vol. 5, No. 2, 2007
[7] Fung and Hsieh, “Hedge Fund Benchmarks: A Risk Based Approach”, Financial Analyst Journal, March 2004
[8] Amenc et al, “Performance of Passive Hedge Fund Replication Strategies”, EDHEC, September 2009
[9] Baele et al, “Flights to safety”, Finance and Economics Discussion Series, Federal Reserve Board, 2014
[10] Jiang and Kelly, “Tail Risk and Hedge Fund Returns”, Chicago Booth Paper No. 12-44, November, 2012
[11] Andrew Lo, “The Adaptive Markets Hypothesis”, The Journal of Portfolio Management, 2004