The benefits from these efficiency gains could flow across the economy, through lower-cost business and retail lending. But there are other relevant public policy questions here as well, including foreign ownership and concerns about the concentration of market power among very few players. Striking a balance between these interests is not a simple task.
After all, the degree of monetary policy accommodation in the euro area is determined not so much by what volume of assets are purchased each month as by the stock of assets held on the Eurosystem balance sheet. And that stock comes to around € trillion in the meantime.