The arrest of a former Goldman Sachs employee at the centre of a criminal case involving the unsanctioned downloading of sophisticated trading software codes has thrust the largely unglamorous world of computerised equity trading into the spotlight.

Sergey Aleynikov, 39, had just started work at Teza Technologies in Chicago, a start-up founded by two former traders with the Citadel hedge fund, when he was arrested on Friday and accused of theft of “trade secrets” and the transportation of those “secrets” to a computer server in Germany.