策略性情緒下的市場績效

Market Performance under Strategic Sentiment

難觀測到與基本面無關的太陽黑子（sunspot） 會造成異質情緒 （idiosyncratic sentiment）投資者形成信念與行動異質性，也會導致金融或經濟多元均衡（multiple equilibria）現象。本文因而發現：股市超額波動性會隨著風險資產需求彈性倒數呈正向變動，也會受到替代以及資訊相對效果影響，而有不同波動方向。不論流動性如何，在精確先天信念或私有信號下，人們的學習會使資訊顯得更具效率性。在成熟市場中，當太陽黑子的私有信號變得更精確時，即使價格變高，資訊交易者還是會積極地交易風險資產；但是先天信念精確度是無法明確揭露資訊交易者風險資產委託單方向。在新興市場裡，不論私有信號或先天信念精確度如何改變，非資訊交易者對資訊交易者的策略反應以及資訊交易者彼此的學習都會造成價格變動對資產委託單方向的影響。

Investors with idiosyncratic sentiment, which is affected by unobserved nonfundament sunspot variables, don’t only form idiosyncratic belief and motive, but also lead to multiple equilibria. Hence, this study finds: excess volatility in stock market positively vary with the inverse of demand elasticity of risky asset. Under precise belief or private signal, learning by agents cause information more efficient. In maturity market, informed traders positively trade risky asset as sunspot private signal become precise, but the precision of belief ambiguously disclosure the direction of order of risky asset. In emerging market, price changes by strategic reactions of uninformed and learning among informed traders affect the direction of orders, no matter what is the precision of belief or private signal.