By Barbara Kollmeyer
MADRID (MarketWatch) -- Shares of Royal Dutch Shell PLC RDS.A +1.19% UK:RDSA -3.53% tumbled 3.3% on Thursday after an oil slick was reportedly spotted near its platforms in the Gulf of Mexico. In a statement, Shell said the company is sending a spill-response vessel and will request flights to moniter the advance, and has also reported the sheen to the National Response Center, run by the U.S. Coast Guard. The slick measures 10 square miles, and media reports said it's about 130 miles southeast of New Orleans. "At this time, the source of this sheen is unknown, and Shell's priority is to respond proactively, safely, and in close coordination with regulatory agencies," Shell said. "Updates will be provided as further action is taken." (Updates with statement from Shell)
