The investigation is focused on companies that use affiliates or brokers to sell coal from mines in the Western U.S. to customers in Asia.That's when the parent company pays government royalties based on the mine price, then the affiliate ships the fuel overseas where it's sold for many times the original price. ___ By The Associated Press(equals) The Dow Jones industrial average rose 48.92 points, or 0.4 percent, to 13,992.97. The Nasdaq composite climbed 28.74 points, or 0.9 percent, to finish the week at 3,193.87. The S&P 500 rose 8.54 points to 1,517.93, closing 0.3 percent up for the week. Benchmark crude for March delivery fell 11 cents to finish at $95.72 per barrel on the New York Mercantile Exchange. It rose as high as $96.57 in the morning. In London, Brent crude, used to price international varieties of oil, rose $1.66 to end at $118.90 a barrel on the ICE Futures exchange. Wholesale gasoline rose 6 cents to finish at $3.06 a gallon. Natural gas fell 1 cent to end at $3.27 per 1,000 cubic feet. Heating oil gained 4 cents to finish at $3.24 a gallon.