I'm not sure that this would slow down HFT, but it might cut costs for consumers. It would definitely be a good idea to have different tick sizes for different

I'm not sure that this would slow down HFT, but it might cut costs for consumers. It would definitely be a good idea to have different tick sizes for different products as it's odd that the most liquid products and the least liquid products might both have a 0.5bps tick size in the US. If you do reduce the tick size you'll need to make some changes to internalization to reduce the toxicity of lit venues.