Synthetic Cross Currency Pair

ForexDictionary explains Synthetic Cross Currency Pair

Synthetic cross currency pairs are still used to trade exotic currencies against each other. For a typical trader, however, synthetic cross currency pairs have several disadvantages. Mainly, they tie up more capital because two trades of equal size must be placed and the job of monitoring the trade is similarly doubled. For most traders, the eight most commonly traded currency pairs are enough, but advanced traders can turn to synthetic cross currency pairs when they run out of regular ones.