XTX Markets, the market-maker spun out of quantitative hedge fund GSA Capital, has become a member of a London-based equity trading venue founded by former Chi-X chief executive Alasdair Haynes.

Its membership of Aquis Exchange underlines the growth of the venue since it started trading in November 2013. About €10.4 billion of equities traded on Aquis in December 2016, up from €4.6 billion the same month a year earlier, according to its website.