(Corrects fifth bullet)
* First-qtr GDP contracted 0.2 pct vs earlier estimate of 0.7 pct
* Tsipras scheduled to meet international creditors at 1700 GMT
* All 10 major S&P 500 sectors in the red
* Apple rises; Netflix trims gains after Icahn comments
* Indexes down: Dow 0.58 pct, S&P 0.39 pct, Nasdaq 0.37 pct
By Tanya Agrawal
June 24 (Reuters) - U.S. stocks fell to session lows in early afternoon trading on Wednesday as the outcome of the negotiations between Greece and its international creditors remained up in the air.
Creditors demanded sweeping changes to Greek Prime Minister Alexis Tsipras' tax and reforms proposals, adding fresh uncertainty to talks aimed at unlocking aid to avert a debt default next week.
Tsipras is scheduled to meet the heads of the European Central Bank, the International Monetary Fund and the European Commission in Brussels before a meeting of euro zone finance ministers at 1300 p.m. ET (1700 GMT).
Greece needs fresh funds to avoid defaulting on a $1.8 billion debt repayment to the IMF on June 30.
"The U.S. market is taking some signals from the weakness in Europe," said John Canally, chief economic strategist at LPL Financial in Boston.
"The situation could set a precedent for other countries wanting to leave the euro zone and that creates some uncertainty that markets don't like."
The U.S. Commerce Department said gross domestic product fell at a 0.2 percent annual rate in the January-March quarter, instead of the 0.7 percent it estimated last month.
Investors have been keeping a keen eye on economic data to see if the U.S. economy has recovered from a slow start at the beginning of the year. The Federal Reserve has said it remains data-dependent and expects to raise rates when it sees a sustained rebound in the economy.
Most economists and top Wall Street banks expect the Fed to raise rates in September as data points to a recovery.
"The Fed is itching to raise rates and just wants to get the first rate hike out of the way," said Canally.
Applications for U.S. home mortgages rose last week as interest rates dipped.
At 12:34 p.m. ET, the Dow Jones industrial average was down 104.5 points, or 0.58 percent, at 18,039.57, the S&P 500 was down 8.37 points, or 0.39 percent, at 2,115.83 and the Nasdaq Composite was down 19.33 points, or 0.37 percent, at 5,140.77.
All of the 10 major S&P 500 sectors were lower, with the materials index leading the declines with a 0.92 percent drop.
Monsanto's 4.3 percent fall weighed the most on the index after the world's largest seed company said it would still pursue an acquisition of Swiss rival Syngenta.
Apple shares rose 1.5 percent to $128.97 after Carl Icahn said that he sees the company representing the same opportunity that Netflix offered several years ago.
Netflix, which rose as much as 3.7 percent after the company's board approved a seven-for-one stock split, trimmed those gains to trade up 0.5 percent at $684.46 after Icahn said his firm had sold the remainder of its stake in the company.
Lennar rose 3.9 percent to $50.95 after the second-largest U.S. homebuilder reported a better-than-expected 33 percent jump in quarterly profit as it sold more homes at higher prices.
Declining issues outnumbered advancing ones on the NYSE by 1,928 to 997. On the Nasdaq, 1,813 issues fell and 869 rose.
The S&P 500 index showed 17 new 52-week highs and two new lows, while the Nasdaq recorded 102 new highs and 21 new lows. (Editing by Don Sebastian)