Narrow Results

In this paper, we analyze whether model risk/asset-specific ambiguity is an issue for institutional investors. For this purpose, we first show how model risk (which turns out to be equivalent to special cases of ambiguity) affects optimal portfolio allocation. Using average portfolio holdings for traditional and alternative asset classes of 119 institutional investors, we then calibrate our model to implicitly determine the ambiguity factors of different asset classes. We find that institutional investors are strongly ambiguity-averse, as documented by a Sharpe ratio that is only 60 percent that of an (unambiguous) efficient portfolio. In line with intuition, we document that equity and bond portfolios have a rather low ambiguity, while alternative investments such as real estate, private equity, and hedge fund investments exhibit a very high ambiguity. These results are robust with regard to the size of the expected returns supposed by the investors.

Real option valuation has traditionally been concerned with investment under project value uncertainty while assuming that the agent has perfect confidence in a specific model. However, agents do not generally have perfect confidence in their model and this ambiguity may affect their decisions. In addition, the value of real investments is not typically fully spanned by tradable assets because markets are incomplete as is typically the case in energy and commodities. In this paper, we account for the agent’s aversion to model ambiguity and address market incompleteness through the notion of robust indifference prices. We derive analytical results for the perpetual option to invest and the linear complementarity problem that the finite-time version of this problem satisfies. Ambiguity aversion has a number of effects on decision making some of which cannot be explained by altering the agent’s risk aversion. For example, ambiguity averse agents are found to exercise real options both earlier and later than their ambiguity neutral counterparts, depending on whether ambiguity stems from uncertainty in the dynamics of the project value or the dynamics of a hedging asset.

Understanding the triggers of individual adaptation behavior is critical for empowering those who are highly vulnerable to climate change. This study explores the effect of ambiguity aversion on adaptation behaviors in the context of climate change. We conduct a field survey among 230 rice farmers in northeastern Thailand to examine the association between elicited ambiguity aversion and the implementation of climate change adaptation. We find that ambiguity aversion does not encourage farmers’ adaptation behaviors and can even discourage the uptake of adaptation strategies. The role of ambiguity aversion varies depending on the characteristics of the adaptation strategy: ambiguity-averse farmers are less likely to adopt adaptation strategies that entail shifts from the status-quo. A deliberate approach is needed to understand farmers’ adaptation behaviors outside the laboratory setting and to reduce ambiguity in the results concerning adaptation to increasing climate risk.

The uncertainty premium is the premium that is derived from not knowing the sure outcome (risk premium) and from not knowing the precise odds of outcomes (ambiguity premium). We generalize Pratt's risk premium to uncertainty premium based on Klibanoff et al.'s (2005) smooth model of ambiguity. We show that the uncertainty premium can decrease with an increase in decision maker's risk aversion. This happens because increasing risk aversion always results in a lower ambiguity premium. The positive ambiguity premium may provide an additional explanation to the equity premium puzzle.

This paper offers an ambiguity-based interpretation of the variance premium — the difference between risk-neutral and objective expectations of market return variance — as a compounding effect of both belief distortion and variance differential regarding the uncertain economic regimes. Our calibrated model can match the variance premium, the equity premium, and the risk-free rate in the data. We find that about 97% of the mean–variance premium can be attributed to ambiguity aversion. A three-way separation among ambiguity aversion, risk aversion, and intertemporal substitution, permitted by the smooth ambiguity preferences, plays a key role in our model’s quantitative performance.

We argue that ambiguous correlation between asset payoffs plays an important role in the occurrence of “flight to quality”, which in some circumstances leads investors with incomplete information to portfolio under-diversification. In this paper, we consider a multi-asset economy with four types of investors who have heterogeneous beliefs on correlation coefficients, and in which ambiguity-averse traders make decisions in a maxmin expected utility framework. A unique general equilibrium presents in four scenarios according to the dispersion of asset quality. We define a measure to gauge the degree of portfolio under-diversification, with which we show that correlation ambiguity will drive less-informed investors to hold a nondiversified portfolio if the correlation coefficient is negative, while a positive correlation drives some less-informed investors to hold a fully diversified portfolio.

Ambiguity aversion has been suggested as a potential explanation for the equity premium puzzle in recent theoretical models. To test this hypothesis, we measure the amount of ambiguity aversion in a large-scale international survey. A comparison to the average equity premia in these countries demonstrates that ambiguity aversion does, indeed, have a significant influence on the amount of equity risk premium, even when controlling for macroeconomic parameters. Finally, we connect differences in ambiguity aversion to differences in uncertainty avoidance, one of Hofstede’s cultural dimensions.

Stocks are riskier than bonds. This causes a risk premium for stocks. That the size of this premium, however, seems to be larger than risk aversion alone can explain the so-called “equity premium puzzle”. One possible explanation is the inclusion of a degree of ambiguity in stock returns to account for an additional ambiguity premium, whose size depends on the degree of ambiguity aversion among investors. It is, however, difficult to test this empirically. In this paper, we compute the first firm-level estimation of equity premium based on the internal rate of return (IRR) approach for a total of N = 28,256 companies in 54 countries worldwide. Using a survey of international data on ambiguity aversion, we find a strong and robust relation between equity premia and ambiguity aversion.

This paper examines how ambiguity aversion and information uncertainty jointly influence the momentum effect across countries. Most countries in our sample exhibit information uncertainty effect, i.e., the momentum effect is stronger for firms with greater uncertainty (e.g., smaller, younger, and more volatile firms). Moreover, we find that such information uncertainty effect is stronger in countries with lower degree of ambiguity aversion. The interaction effect of uncertainty and ambiguity aversion is mainly driven by losers, suggesting the information avoidance or “Ostrich Effect”. We offer two possible explanations for this result based on the potential impacts of ambiguity aversion on information reaction and information seeking.

We study a model that relates dividend payout policy to behavioral issues based on the ideas of mental accounting. A panel analysis across 29 countries and over 43,000 firm-years demonstrates that our model studying the relation between dividends and patience, loss aversion, and ambiguity aversion can be verified empirically. Our paper seems to be the first that highlights empirically in a straightforward way the relevance of behavioral patterns as important determinants for corporate dividend policy, while previous empirical studies could tackle this issue only indirectly. With several robustness tests we also address potential doubts concerning the quality of our data and analyze further implications of our theory.

Previous literature on cash management has revealed that firms hoard cash to protect themselves against external financing constraints that might limit future capital budgeting policies. In a theoretical model based on this finding, we analyze how investors’ attitude toward uncertain investment returns affects the valuation of cash and the amount of cash holdings. Subsequently, we show empirically that cash holdings become less valuable with increasing ambiguity aversion in line with our model. We also demonstrate that managers react accordingly and lower cash holdings if their investors tend to be more ambiguity-averse. Several robustness tests confirm our findings.