The problems at the NYSE began shortly before noon and were attributed to an unspecified "internal technical issue."
"NYSE has temporarily suspended trading in all symbols," the market said in a message to traders. "All open orders will be cancelled."
The market said it chose to halt trading to avoid problems related to the issue and that it was not the result of a cyber breach.
The Securities and Exchange Commission said is it closely monitoring the situation and is in contact with the NYSE.
The disruption was the second of the day for the exchange.
Earlier in the trading session, connectivity to three of the NYSE's connection points for computerized trading were hit by a fault that caused trading in about 200 stocks to be halted. Two of the affected gateways were returned to service and one was planned to be restored at the end of the Wednesday session.
Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is martyn_williams@idg.com