Before revision:  We find substantial costs and preference heterogeneity and that having many firmsis crucial for good market outcomes . Counterfactuals show that simplifying the current mechanism with English auctions and "shutting down" risk ratings increase pensions, but only for high-savers.
After revision:  We find substantial costs and preference heterogeneity , and because there are many firms, the market performs well . Counterfactuals show that simplifying the current mechanism with English auctions and "shutting down" risk ratings increase pensions, but only for high-savers.