Abstract: Based on the Almost Stochastic Dominance (Almost Stochastic Dominance, ASD(2013)) criterion, which focuses on maximizing investors' expected utility, this paper analyzes the performance of the stock markets and ten-year government bonds in China and the United States under different economic cycles and holding periods. The study finds that rational investors in China are risk-averse, prioritizing asset stability over returns, and their decisions do not easily change with economic cycles and holding periods. In contrast, rational investors in the United States are risk-neutral, more concerned with asset returns, and adjust their decisions according to economic cycles and holding periods. This paper identifies social and political stability, investors' confidence in the government, social culture and psychology, financial education and professional training, and financial technology as significant factors contributing to the decision-making differences between rational investors in China and the United States. The study also suggests that as the Chinese market matures and the explicit differences between it and the U.S. risk market diminish, rational investors will not become risk-neutral but may moderately relax their risk aversion within controllable limits.

Key words: Almost Stochastic Dominance, Rational Investors, Risk Market, Decision Differences