MOSCOW () -- The ruble gained four points against the dollar Thursday during trading on the Moscow Interbank Currency Exchange, closing at 2,156 per dollar. Net trading volume was $29.55 million, with initial supply of $168.75 million and initial demand for $143.2 million. Twenty-two banks participated in the trading. The ruble gained 20 points against the Deutsche mark, closing at 1,387 per mark.