Nex Group, Michael Spencer's trading technology firm that was formed out of a merger of the voice-broking arm of Nex and Icap last year, said Jenny Knott had decided to step down and would be replaced by Ken Pigaga, global chief operating officer of Nex.
Pigaga will hand over his chief operating officer responsibilities to Samantha Wren, who was named group chief financial officer in May following the departure of Stuart Bridges.
Earlier this month, the company said profitability at its Nex Optimisation business would be hit as it prepares for Mifid II rules to come into effect. The post-trade division accounts for nearly half of the group's total profits.
During her time at Nex, Spencer said Knott "evolved our client strategy and implemented a simpler and more unified operating model, identifying and adopting new and emerging technologies".
"Jenny's significant contribution will have an enduring impact on the business and we wish her every success for the future," Spencer said.
Knott is the latest of a number of senior executives to leave the company in recent months, but Spencer said the company now "has the right management team in place to deliver on our strategy".
Knott said: "I am proud of the achievements of the Nex Optimisation leadership team. In just over two years we have transformed ourselves to transform the industry."
Having redesigned Nex Optimisation, it is now time to let them execute on the new structure and for me to pursue new entrepreneurial opportunities.