The Nasdaq stock exchange on Thursday halted trading in all Nasdaq-listed shares due to a problem distributing stock price quotes. U.S. stocks rose slightly.

All traffic through Nasdaq stopped at 12:14 p.m. EDT, the exchange said on its website.

The Securities and Exchange Commission said it was monitoring the situation, while Nasdaq, owned by NASDAQ OMX Group NDAQ.O, urged securities firms to route all their trades elsewhere.

COMMENTS:

JIM GORMAN, SPOKESMAN FOR EXCHANGE OPERATOR DIRECT EDGE IN NEW JERSEY:

"We are cooperating with a street-wide halt and our systems are operating normally."

ANTHONY CONROY, HEAD TRADER FOR CONVERGEX GROUP, A GLOBAL BROKERAGE COMPANY, IN NEW YORK, NY: In response to: has it had a big impact on your trading today?

"So far, yes. Especially anytime you have indecision, there's nervousness, so that nervousness is creating a little bit of volatility in the markets, and we're trying to figure out because you just don't know- is it going to be a reopening, are we down for the rest of the day?"

ROBERT STEIN, GLOBAL HEAD OF ASSET MANAGEMENT AT ASTOR ASSET MANAGEMENT LLC IN CHICAGO, IL:

"It's a good day to have another glitch, if you will, a quiet August with an upward bias in the market, so it could go unnoticed."

"It hasn't created any additional type of volatility in the markets either, so we're just sort of waiting to hear."

In response to: how significant a glitch do you think this could be?

"Not very. You would probably see more volatility if it was the type of glitch that was erroneous trades or people having uncertainty or lack of clarity on what their positions were. The biggest problem is when you're not sure what your positions are, as opposed to connectivity being down ...

"The bigger deal is when you're flying blind."

JASON WEISBERG, managing director at Seaport Securities Corp in NY:

"Technology has flaws, but it could happen to anyone. It's their turn in the wheel. The reason the Stock Exchange (halted securities) was out of courtesy. If I had to guess, it is clearly out of courtesy and not because they don't want to step on their competitors. I don't think they want to do it in that fashion.

It slows thing down in Nasdaq stocks (trading on the NYSE), but that being said, it does make the case for listing shares on the new York Stock Exchange because there are humans to trade. And it does make a case for a need in an open outcry market in the U.S. equity market."

(Americas Economics and Markets Desk)