This paper investigates the trading behavior of ambiguity-loving investors and the corresponding impacts on asset price. The ambiguity-loving attitude increases investors' willingness to participate in the risky asset market. Their rising participation gradually crowds out ambiguity-averse and sophisticated investors, extending their nonparticipation region. When the market supply is small, the discontinuous and non-unique properties of ambiguity-loving investors' demand mapping can cause flat ranges in the equilibrium price. When the market supply is moderate or large, an increase in the fraction of ambiguity-loving investors or ambiguity level reduces equity premium. We find the effect of ambiguity-loving attitudes remains with short-sales constraints except for ambiguity-loving investors' positions and the equity premium. Their positions shrink, and equity premium decreases when the market supply is small. Besides, the rising fraction of ambiguity-level investors and ambiguity level increases equity premium when ambiguity-loving investors with heterogenous opinions only sell the risky asset.

We demonstrate that limited participation can arise endogenously in the presence of model uncertainty. Our model generates novel predictions on how limited participation relates to equity premium and diversification discount. When the dispersion in investors?model uncertainty is small, full participation prevails in equilibrium. In this case, equity premium is unrelated to model uncertainty dispersion and a conglomerate trades at a price equal to the sum of its single segment counterparts. When model uncertainty dispersion is large, however, investors with relatively high uncertainty optimally choose to stay sidelined in equilibrium. In this case, equity premium can decrease with model uncertainty dispersion. This is in sharp contrast to the understanding in the existing literature that limited participation leads to higher equity premium. Moreover, when limited participation occurs, a conglomerate trades at a discount relative to its single segment counterparts. The discount increases in model uncertainty dispersion and is positively related to the proportion of investors not participating in the markets.