Traders will have to explain to regulators how their computer algorithms are designed and work as part of the European Commission's widespread overhaul of MiFID.
With the EC set to publish its MiFID II plans next week, a draft of the public consultation has been seen by the press, revealing a series of measures designed to reign in the controversial practice of high-frequency trading.
Under the proposals, as well as being forced to tell regulators about their algorithms, all high-frequency traders over a specified minimum quantitative threshold will have to be authorised as investment firms.
These firms, as well as companies providing "sponsored access" to automated traders, will have to put in place "robust risk controls" to mitigate possible system errors.
Meanwhile, operators of trading venues will have in place proper controls and arrangements to mitigate the risk of errors generated by automated trading leading to disorderly trading - such as circuit breakers. Under the proposals, venue operators also have to give "equal and fair access" to market participants to co-location services.
As it seeks to cast light on over-the-counter derivatives trading, the EC is also planning a to create a new category of "organised trading facility". Banks will have to change their private trading systems to formal venues, publicly posting prices at the end of each day.
On dark pools, the EC is more circumspect, saying that their increased use raises "regulatory concerns but only "merits ongoing observation by regulators and clear boundaries".
Mifid review: EC proposals at a glance - FT (subscription)