What a high or low reading means
A high dollar score means speculators are net-short the foreign currency against the dollar across several major pairs at once: broad dollar buying. A low score means speculators are dollar-bearish across the board. Because each currency is ranked against its own history, no single large market can dominate; the index rises only when positioning is extreme across many pairs. The zero line is the theoretical floor (every currency at the 100th percentile of net-long foreign currency) and 100 the ceiling (every currency at the 0th percentile, net-short foreign currency), though in practice the index stays between roughly 30 and 70.