NEW YORK—The U.S. Treasuries market took investors on a bumpy ride in 2020, with yields plunging to historic lows in the early part of the year before a partial grind back in the second half. Investors are looking for yields to edge up further as the calendar flips to 2021. Expectations that a vaccine against COVID-19 will spur an economic rebound in 2021 have pushed some investors out of Treasuries and other safe-haven assets in recent months and helped lift yields, which move inversely to bond prices, near their post-pandemic highs just under 1 percent. Still, they are well off the levels seen at the beginning of the year, when benchmark 10-year Treasuries yielded closer to 2 percent. The post-pandemic drop in Treasury yields, spurred by unprecedented U.S. Federal Reserve support, had wide-ranging repercussions, forcing investors to rethink the role of bonds as a hedge against stock gyrations and spurring …