The head of the key post-trade division at Michael Spencer’s NEX Group has stepped down — two weeks after the financial technology company revealed a squeeze on profitability that dented its share price.

NEX, which was formed at the start of the year following the sale of Icap's voice-broking business to rival interdealer broker Tullett Prebon, said in a statement that Jenny Knott has decided to step down as chief executive of its optimisation division.