Silver prices that have slumped from a 31-year high in April may drop a further 11 per cent by the end of next month, according to technical analysis by Fain Shaffer, the president of Infinity Trading Corp. The September futures contract traded on the Comex in New York has completed a so-called head-and-shoulders pattern with prices dropping below the 150-day moving average of $34.08 (Dh125.17) an ounce on Monday, Shaffer said in a telephone interview from Medford, Oregon. The move signals prices may slip to $30 by the end of July, he said. \"We may see a freefall if it falls below the 200-day moving average\" of $31.50, said Shaffer, who used technical analysis of the cotton market in May to correctly forecast that the commodity would fall to $1.20 a pound. The silver market \"has not been able to resume an uptrend since the big selloff in early May,\" he said.