NEW YORK -- Nasdaq has halted trading because of a technical problem.
The exchange sent out an alert to traders saying that trading was being halted until further notice because of problems with a quote dissemination system.
Nasdaq said it wouldn't be canceling any open orders, but that customers could cancel orders if they wanted to.
Nasdaq sent out an update at 1pm saying trading would reopen "at a time to be determined."
The Nasdaq composite index was frozen at 3,631.17 as of 1:20 p.m., up 31.38 for the day. The index is up 20 percent so far this year.
Securities and Exchange Commission spokesman John Nester said: "We are monitoring the situation and are in close contact with the exchanges."