* Investors focus on U.S. fiscal risks, Greek uncertainty * Stocks fall around the world * Commodities ease on worry over U.S. growth * Euro down, dollar falls vs yen NEW YORK, Nov 28 (Reuters) - Stocks, commodities and the euro fell on Wednesday on investor frustration with a lack of progress in U.S. budget talks and as doubts crept in over Greece's new debt deal. Lack of progress in the U.S. budget talks compounded investor caution about the plan agreed late Monday by the EU, ECB and IMF to reduce Greece's debts. The deal opened the way for more aid to Athens to avoid a chaotic default, but details remain unclear and analysts worry it will not do enough to make Greece's debt viable. U.S. Senate Majority Leader Harry Reid expressed disappointment on Tuesday over the progress of talks between Democrats and Republicans on avoiding the so called "fiscal cliff" consisiting of $600 billion in automatic tax rises and spending cuts due to start early next year. Chief executives from top U.S. corporations, including Goldman Sachs, Deloitte LLP, and Caterpillar Inc, will meet with President Barack Obama on Wednesday to discuss U.S. fiscal problems, the White House said. "These CEOs know that the market will selloff without any resolution, so I think it's encouraging that they are meeting with the President. But more importantly, the market would want to see them actually meeting with the congressional leadership, those that are actually making negotiations and compromises," said Sal Arnuk, co-founder at Themis Trading at Chatham, New Jersey. The Dow Jones industrial average was down 85.89 points, or 0.67 percent, at 12,792.24. The Standard & Poor's 500 Index was down 10.83 points, or 0.77 percent, at 1,388.11. The Nasdaq Composite Index was down 25.13 points, or 0.85 percent, at 2,942.66. The MSCI index of global stocks was down 0.8 percent. In currency markets, the euro was down 0.6 percent to $1.28917 as some traders bet recent gains made in the run up to the Greek deal were too far, too fast. Commodity markets also reflected the worries of a possible U.S. budget crisis and how this could tip the world's biggest economy into recession. Gold fell for a third straight day, copper dropped from a three-week high and Brent crude lost $1.15 cents to $108.70 per barrel. U.S. crude oil futures fell 1.6 percent to $85.56. U.S. data did nothing to improve sentiment. New U.S. single-family home sales fell slightly in October and the government revised sharply lower its estimate for the prior month's sales, casting a small shadow over what has been one of the brighter spots in the U.S. economy..