Europe’s new trading and transparency regime promised a lot. For the first time outside the equity market, investors would have data enabling them to properly compare prices, benchmark their trades and gauge market liquidity.

So far, those promises have not been kept. The data called for by the second Markets in Financial Instruments Directive (Mifid II) does exist, but critics are scathing about how it is being delivered. Regulators are now scrutinising the services designed to perform that