HFTs would likely have their own exchange memberships so as to reduce transaction costs (as their buy-sell spread are as low as Rs. 0.10 as mentioned in this article). During the past year, many international HFT firms (Virtu Trading, XTX Securities, and Jump Trading) started operations in India and all have taken up their own exchange memberships (as mentioned in this article). Even other HFT firms that are active in India (like AlphaGrep, Tower Research, Centillion Research, Graviton Research Capital, etc) also have their own exchange memberships. Also, another way these HFT firms might be saving costs is by moving their registered office to Gift City as their is a stamp duty waiver for trading happening via there.