The Manhattan district attorney's office is investigating whether a former technology executive stole computer code from a high-profile trading firm and used it to benefit a rival, according to people briefed on the probe.

At issue is a firm's computer code - closely guarded systems software and trading algorithms that determine how orders to buy and sell securities navigate the market's complex infrastructure. Trading code can help determine a firm's success or failure and has been, at times, a focus of intrigue.