A prop trading lobby group has warned the European Union that legislation to curb high-frequency trading will “undo the good work” already done on regulatory reforms.

Late last week, Markus Ferber, a German member of the European parliament who is responsible for guiding the revised version of the Markets in Financial Instruments Directive (MiFID) through to the next stage of approval in Europe, hinted in a report at firmer proposals to tackle the growth of high-frequency trading.

“We would be concerned by any proposals that could undo the good work to date on regulatory reforms—such as the introduction of minimum resting periods, which could result in a decrease in liquidity by hampering effective risk management,” said Remco Lenterman, chairman of the European Principal Traders’ Association (Epta).

The report has been highly anticipated by traders, brokers and exchanges, as it could influence how Europe votes on the revised version of MiFID, which is the European legislation that will deal with high-frequency trading.

In it, Ferber called for “a minimum period for keeping an order before it can be cancelled, a so-called circuit-breaker” as well as “additional cancellation fees ought to be introduced so ultra-fast transactions can be rendered less interesting and excessive speculation can be contained”.

Ferber wants traders to keep orders for a minimum period, possibly at least 500 milliseconds, to make it more likely for a buyer to be found. High-frequency traders have been criticized for ‘quote stuffing’, when algorithms flood the market with orders only for them to be cancelled fractions of a second later. This can artificially move prices for the trader to then capitalize with a real order.

However, the Epta chairman, who is also managing director of Dutch high-frequency trading firm IMC, says that automated trading technology has been pivotal in improving market quality over the last decade.

“We will continue to engage constructively with the European parliament and all other political stakeholders in the interest of achieving better financial regulation for the benefit of all,” said Lenterman.

Epta says that academic research shows high-freqency trading has increased liquidity, lowered spreads, reduced the cost of trading and enhanced market efficiency. As a result, it says post-trade costs have gone down by over 50% and volatility has been dampened.

Epta, a lobby group formed last year under the auspices of trade organization the Futures Industry Association and based in Brussels, includes the biggest high-frequency firms such as Getco and Citadel of the U.S. and Optiver, IMC and Flow Traders in the Netherlands.

High-frequency trading firms have been in the crosshairs of some sectors of the financial markets as well as politicians for their perceived role in destabilizing the markets.