(Adds background on Thursday's error, Aleynikov update, byline)

By Jonathan Spicer and Ellis Mnyandu

NEW YORK, July 6 (Reuters) - The New York Stock Exchange said on Monday there was no connection between an alleged security breach at Goldman Sachs (GS.N: Quote, Profile, Research) and an error that dropped the big investment bank from a trading report the exchange issued last week.

Nor are they related to a technical problem that hit Big Board floor brokers and extended the trading day by 15 minutes last Thursday, an NYSE spokesman said.

Former Goldman Sachs computer programmer Sergey Aleynikov, who was released on bail on Monday, is accused of stealing secret trading codes from the New York-based bank. [ID:nN06255904] [ID:nN05180222]

The Big Board, run by NYSE Euronext (NYX.PA: Quote, Profile, Research)(NYX.N: Quote, Profile, Research), issued a report last week that inexplicably did not list Goldman among its most active program trading firms in the week ended June 26. Goldman often tops the weekly list, which measures computer-driven orders for large baskets of stocks.

"It appears Goldman Sachs reported data correctly, and that due to a system problem on our part, the firm's individual program trading was not included in our weekly report," NYSE spokesman Ray Pellecchia said.

The exchange will re-issue the report with the Goldman Sachs data later this week.

Pellecchia said the Aleynikov case was not related to NYSE's program trading report error. He had no comment on whether the exchange was in discussions with Goldman about the alleged security breach.