A former Goldman Sachs Group Inc computer programer accused of stealing secret trading codes from the financial firm was being held in federal custody on Monday, pending the posting of $750,000 bail.

Sergey Aleynikov, 39, has been in custody since his Friday arrest on theft of trade secrets charges.

He is accused of misusing computer codes that belong to his former employer, a New York-based financial institution that authorities did not identify in court papers but sources say is Goldman Sachs.

A transcript of Aleynikov's appearance before U.S. Magistrate Kevin Nathaniel Fox in Manhattan on Saturday also shows that Aleynikov worked for Goldman.

His lawyer said at that proceeding that Aleynikov told authorities after his arrest that he did not intend to sell the information or use it contrary to my employment agreement with Goldman Sachs.

Goldman has not seen its business or clients harmed by the purported computer breach, a source familiar with the situation said on Monday. The firm declined to comment.

The case could shed light on the workings of intricate trading systems developed by Goldman. It also raises questions about the security of lucrative Wall Street proprietary trading operations.

However, the New York Stock Exchange said on Monday there was no connection between the alleged security breach and an error that dropped Goldman from a trading report the NYSE issued last week.

Aleynikov, a Russian immigrant living in New Jersey, was arrested on Friday night by FBI agents as he got off a flight at Newark Liberty International Airport, according to an FBI affidavit filed in the case.

His lawyer, Sabrina Shroff, said Monday afternoon that she hoped Aleynikov would be released shortly. She said the bail conditions could not be met immediately because he was arrested over a holiday weekend when most court offices were closed.

I am hoping he will be out soon, she said.

Aleynikov was being held at the Metropolitan Detention Center in Brooklyn, according to the federal Bureau of Prisons website and an officer at the jail.

Terms of his bail require a $750,000 personal recognizance bond to be secured by three financially responsible people.

The bail also includes $75,000 in cash, and Aleynikov was ordered to surrender his travel documents and not to access the computer data at issue in the case.

A preliminary hearing was scheduled for August 3.

Authorities contend Aleynikov stole codes used for sophisticated automated stock and commodities trading. They say Aleynikov, who earned $400,000 a year at Goldman, improperly copied proprietary computer code and then uploaded it to a computer server in Germany.

After he was arrested, he told authorities he had only intended to collect open source files on which he had worked but later realized that he had obtained more files than he intended, the FBI agent said in the court papers.

The FBI said Aleynikov worked at the financial institution from May 2007 until June 5, when he left to work for a new company focused on high-volume automated trading.

Aleynikov's wife, Elina, told Reuters on Sunday that her husband is innocent. She said in a phone interview from the couple's New Jersey home that her husband worked hard for Goldman and has been a good citizen who has lived in the United States for 19 years.

(Reporting by Martha Graybow; additional reporting by Jonathan Spicer and Elinor Comlay; Editing by Gerald E. McCormick, Richard Chang, Tim Dobbyn)