Overall, 72 subjects invest their endowment in four risky assets. Each com-bination of assets yields the same expected return and variance of returns. Illusion of expertise prevails when one prefers nevertheless the self-selected portfolio. After being randomly assigned to groups of four...

Experimental studies of the WTP-WTA gap avoid social trading by implementing an incentive compatible mechanism for each individual trader. We compare a traditional random price mechanism and a novel elicitation mechanism preserving social trading, without sacrificing mutual incentive...