The dollar dipped to a near three-week low against the yen in thin year-end volume on Tuesday as investors favored riskier assets, led by renewed optimism about global growth. The greenback was off 0.1% at 108.77 against the Japanese yen , on track for its third straight session of losses and within a whisker of Monday's 108.74, the weakest since Dec. 12. The dollar index (DXY), which measures the currency against a basket of rivals, was flat at 96.728 in early Asian trade. On Friday, the index had suffered its biggest one-day fall since March, which left its gains for the year at under 0.6%, compared with returns of 4.4% in 2018. It is now on track for the smallest rise since 2013. Encouraging news on the Sino-U.S. trade deal boosted risk sentiment in currency markets overnight. The White House's trade adviser, Peter Navarro, on Monday said the U.S.-China Phase 1 trade deal would likely be signed in the next week, but said confirmation would come from President Donald Trump or the U.S. Trade Representative. Increased optimism about U.S.-China trade relations and an improved global growth outlook drove investors out of other safe-haven assets like Treasury bonds while the risk-sensitive Australian and New Zealand dollars jumped to five-month highs.