* Nasdaq halts trading because of technical issues
* Hewlett-Packard weighs on Dow after revenue comments
* Dow up 0.4 pct, S&P up 0.7 pct, last up Nasdaq 0.9 pct
By Ryan Vlastelica
NEW YORK, Aug 22 (Reuters) - Trading was halted on the Nasdaq, the second-largest U.S. stock exchange, shortly after noon on Thursday because of technical problems, while stocks rose as other U.S. markets continued to operate.
All traffic through Nasdaq stopped at 12:14 p.m. (1614 GMT), the exchange said on its website, adding that trading in all Nasdaq-listed shares would be halted until further notice.
The U.S. Securities and Exchange Commission said it was monitoring the situation, while Nasdaq, owned by NASDAQ OMX Group, urged securities firms to route all their trades elsewhere.
"We're in the moment of unknown right now. We see bumps (in trading) often, but they're usually brief and rarely this broad based," said Frank Davis, director of sales and trading at LEK Securities in New York. "We're trying to figure out when things will get cleaned up."
The Dow Jones industrial average was up 62.89 points, or 0.42 percent, at 14,960.44. The Standard & Poor's 500 Index was up 12.13 points, or 0.74 percent, at 1,654.93.
The Nasdaq Composite Index was up 31.38 points, or 0.87 percent, at 3,631.17 when the trading halt began, affecting stocks of such well-known shares as Apple, Microsoft and Amazon.com.
The New York Stock Exchange continued to operate. The Dow industrials rose for the first time in seven sessions after upbeat data from the world's top economies overshadowed nervousness over the winding down of the Federal Reserve's stimulus program.
Gains in the Dow were limited by Hewlett-Packard, which dropped 12 percent to $22.23 a day after reporting a decline in the Enterprise Group's revenue. The group is the computer company's second-largest division and a critical component of Chief Executive Meg Whitman's plan to transform the company.