Futures trend higher ahead of economic data

(Reuters) - Canada's main stock index was set to open higher on Tuesday, reversing losses from the previous session, ahead of economic data including trade balance and building permits. The country's December trade surplus is expected to have narrowed after posting its first surplus in more than two years in November. Also, markets will watch to see if exports can maintain their strength, as the sector has been a key one for the Bank of Canada's outlook. The data is due at 8:30 a.m. ET. Canada's