We analyze theoretically and empirically the implications of information asymmetry for equilibrium asset pricing and portfolio choice. In our partially revealing dynamic rational expectations equilibrium, portfolio separation fails, and indexing is not optimal. We show how uninformed investors should structure their portfolios, using the information contained in prices to cope with winner’s curse problems. We implement empirically this price- contingent portfolio strategy. Consistent with our theory, the strategy outperforms economically and statistically the index. While momentum can arise in the model, in the data, the momentum strategy does not outperform the price-contingent strategy, as predicted by the theory.

Experimental evidence has consistently confirmed the ability of uninformed traders, even novices, to infer information from the trading process. After contrasting brain activation in subjects watching markets with and without insiders, we hypothesize that Theory of Mind (ToM) helps explain this pattern, where ToM refers to the human capacity to discern malicious or benevolent intent. We find that skill in predicting price changes in markets with insiders correlates with scores on two ToM tests. We document GARCH‐like persistence in transaction price changes that may help investors read markets when there are insiders.