* S&P 500 pulls back a bit after hitting intraday record
* Vertex soars after clinical trial; Micron up on outlook
* Consumer confidence at six-year high; new home sales top expectations
* Dow off 0.5 pct; S&P 500 off 0.3 pct; Nasdaq up 0.1 pct (Updates to mid-afternoon, changes byline)
By Chuck Mikolajczak
NEW YORK, June 24 (Reuters) - U.S. stocks mostly slipped on Tuesday as earlier gains from economic data faded, but the Nasdaq advanced as a result of gains in biotech shares.
In the latest signs of improving economic conditions, consumer confidence surged more than expected in June, while new home sales in May rose more than anticipated in the latest evidence that the economy has regained momentum after stalling during harsh winter conditions.
The market's earlier gains had lifted the S&P 500 as high as 1,968.17, another intraday record.
"The market obviously responded well to the good economic data earlier - the housing data and of course, the consumer confidence," said Peter Cardillo, chief market economist at Rockwell Global Capital in New York.
"But the market is basically in a standstill here. I kind of suspect this is what we are going to see as the quarter comes to a draw."
Consumer confidence hit its highest level since January 2008 in June, while new home sales jumped 18.6 percent to a six-year high in May. The PHLX Housing Index rose 1.3 percent.
In another snapshot of the housing sector, the S&P/Case-Shiller composite index showed single-family home prices rose less than expected in April.
The major U.S. stock indexes were also held in check by concerns about an escalation of the conflict in Iraq. U.S. Secretary of State John Kerry urged leaders of Iraq's autonomous Kurdish region on Tuesday to stand with Baghdad in the face of a Sunni insurgent onslaught that threatens to destroy the country.
The Dow Jones industrial average fell 76.91 points or 0.45 percent, to 16,860.35. The S&P 500 lost 5.65 points or 0.29 percent, to 1,956.96. The Nasdaq Composite added 4.04 points or 0.09 percent, to 4,372.72.
IntercontinentalExchange Inc was the S&P 500's worst performer, sliding 4 percent to $190.36 after Wells Fargo downgraded the stock to "market perform" from "outperform."
The S&P financial sector index slipped 0.37 percent. Financial stocks also weighed on the Dow industrials, with American Express Co down 0.8 percent at $94.78, Goldman Sachs Group Inc down 0.8 percent at $168.90 and JPMorgan Chase & Co down 0.9 percent at $57.69.
Biotech shares helped buoy the Nasdaq, sparked by a 40 percent surge in Vertex Pharmaceuticals Inc to $93.28 on heavy volume. The Nasdaq Biotech Index climbed 1.7 percent.
Vertex said a combination of drugs designed to treat cystic fibrosis succeeded in improving lung function in a pair of closely watched late-stage clinical trials.
Micron Technology Inc also supported the Nasdaq, rising 4.5 percent to $32.67 a day after the memory chipmaker gave a revenue outlook that exceeded analysts' expectations.
On the downside, Walgreen Co shares fell 0.6 percent to $73.31 after the largest U.S. drugstore chain reported its third-quarter results. Walgreen withdrew its 2016 profit and revenue forecasts, citing the need to work out several aspects of its planned acquisition of Alliance Boots Holdings Ltd (Reporting by Chuck Mikolajczak; Editing by Jan Paschal)