This paper analyses a situation where market designers create new trading platforms and traders learn to select among them. We ask whether 'Walrasian' platforms, leading to market-clearing trading outcomes, will dominate the market in the long run. If several market designers are competing, we...

We consider a pure exchange economy, where for each good several trading institutions are available, only one of which is market-clearing. The other feasible trading institutions lead to rationing. To learn on which trading institutions to coordinate, traders follow behavioural rules of thumb...