Hedge funds have struggled badly in 2018, but would be faring far worse were they not on the right side of two of the most reliable trades of the year: a flattening U.S. yield curve and a stronger dollar. Both trends remain in place, and as the latest data show, speculators look like holding onto them for the rest of the year. Funds increased their net long dollar position against a range of developed and emerging-market currencies by nearly $2 billion to $32.09 billion in the week to Dec. 4, according to Commodity Futures Trading Commission figures.