Alan Gerber and others write,

Agreeableness is strongly, and consistently, associated with liberal economic positions and Emotional Stability is strongly associated with conservative economic positions.

… while previous research has rightly identified Conscientiousness and Openness as the traits most
consistently related to ideology, our analysis shows that the other Big Five traits—particularly Emotional
Stability and Agreeableness—significantly and substantially affect political attitudes.

Pointer from Tyler Cowen.

The authors departed from previous research by separating issues into economic and social issues. By not confounding the two, they find different patterns of relationships between personality traits and conservatism. People who dislike markets tend to score higher on agreeableness, meaning that they like to be seen as pleasing to others. They tend to score low on emotional stability, meaning that they are prone to worry and fear.