[semiquaver]

Most HFTs primarily engage in market making (matching buyers and sellers) which absolutely is a very useful and necessary function to society unless your position is that markets should not exist.

https://en.m.wikipedia.org/wiki/Market_maker

[afiori]

You could hold the position that markets are good but not everything should have a market.

For example you can forbid futures and derivatives without forbidding good old stock trading.

[bostik]

I'm against pure speculation, but forbidding futures outright would feel ... wrong. Locking prices for contracts up front is a useful thing.

However, it might be much more interesting, and societally more beneficial, to require that anyone trading in commodities futures must have, at all times, the facility to take delivery of the contracts. The upper limit of exposure for a trading desk would therefore be bound by the capacity of their physical infrastructure.

[cturner]

That would lead to wider spreads. Then, liquidity would move to another country that did not impose that rule.

[kortilla]

Futures are massively useful to both halves in commodities markets (producers and consumers). Why would you want to ban them?