NEW YORK, July 6 (Reuters) - A former Goldman Sachs GS.N computer programmer accused of stealing secret trading codes from the investment bank was being held in federal custody on Monday, pending the posting of $750,000 bail.

Sergey Aleynikov, 39, was ordered by U.S. Magistrate Kevin Nathaniel Fox in Manhattan on Saturday to post a $750,000 personal recognizance bond to be secured by three financially responsible people.

The bond also was to include $75,000 in cash, and Aleynikov was ordered to surrender his passport.

Aleynikov, a Russian immigrant living in New Jersey, was arrested on Friday night by FBI agents at Newark Liberty International Airport after returning from Chicago, according to court documents. [ID:nN05180222]

He is accused of “theft of trade secrets” related to computer codes used for automated stock and commodities trading at an unspecified financial institution.

Sources familiar with the situation have told Reuters columnist Matthew Goldstein that the financial institution is Goldman Sachs.

A Goldman representative declined to comment on Monday. A lawyer for Aleynikov, Sabrina Shroff, also declined to comment.

Authorities contend that Aleynikov improperly copied a financial institution’s proprietary computer code and then uploaded it to a computer server in Germany.

In court papers, an FBI agent said Aleynikov worked at an unspecified financial institution as a programmer from May 2007 until June 5, when he left to work for a new company focused on high-volume automated trading.

The case could shed light on the intricate trading systems developed by Goldman, and also raises questions about the security of Wall Street’s proprietary trading operations.

Aleynikov’s wife, Elina, told Reuters on Sunday that her husband is innocent.

Speaking in a phone interview from the couple’s New Jersey home, she said her husband worked hard for Goldman and has been a good citizen who has lived in the United States for 19 years.

Aleynikov was being held at the Metropolitan Detention Center in Brooklyn as of Monday morning, according to the federal Bureau of Prisons website and an officer at the jail. (Reporting by Martha Graybow; Editing by Tim Dobbyn)