A Fallen Wall Street Programmer Tells His Side

Sergey Aleynikov, a former Goldman Sachs computer programmer, has had a complicated journey since being convicted of stealing computer code from the bank. The latest chapter came on Thursday in the form of a profile in Vanity Fair.

In the article by Michael Lewis â€" the second half of which will be published online on Friday â€" Mr. Aleynikov tells his version of what happened when he downloaded computer code from Goldman before leaving for a job at a high-frequency trading firm, where he planned to create a rival trading platform.

His motivation in downloading the files, which contained open-source code mingled with code that was proprietary to Goldman, was to disentangle the two in case he needed to remind himself later how he had done so, Mr. Aleynikov told the F.B.I., according to the article. Still, he knew he was making waves at Goldman.

“I knew that they wouldn’t be happy about it,” Mr. Aleynikov told Mr. Lewis. Asked how he felt at the time, he recalled: “It felt like speeding. Speeding in the car.”

Mr. Aleynikov is also critical of Goldman’s approach to its software. A boss was “tense” when Mr. Aleynikov asked if he could return free software that he had modified back to the Internet, as was common practice with open-source code, he said. “He said it was now Goldman’s property,” Mr. Aleynikov recalled of the boss.

Mr. Aleynikov, a Russian immigrant who proved to be a standout at Goldman, said he grew frustrated working on Goldman’s computer platform. “I had a feeling no one at Goldman really knows how it works as a whole, and they are just uncomfortable admitting that,” he said in the article.

A jury found Mr. Aleynikov guilty in 2010, and he was sentenced to eight years in prison. But an appeals court overturned that conviction last year, finding the case was based on a misuse of federal corporate espionage laws. Months later, he was charged with state crimes.

In the Vanity Fair article, Mr. Aleynikov contends that the F.B.I. and Goldman did not have a full understanding of the issue. “He didn’t seem to know anything about high-frequency trading or source code,” Mr. Aleynikov said of the F.B.I. agent in charge of the case.

In the trial, Mr. Lewis writes, Goldman’s role “was to make genuine understanding even more difficult.”

In a statement to Vanity Fair, Goldman said it had “spent millions of dollars and tens of thousands of hours developing the proprietary source code and technology used in our market-making business.” Goldman added that it “restricts access to proprietary technology to those employees whose duties designing and maintaining the technology require such access.”