OTTAWA—Canada's economy expanded at a 3.9% annualized pace in January through March, the fastest clip in a year and more than double the rate in the U.S., as businesses replenished inventories and boosted investment spending and exports rose while consumer and government spending stalled, Statistics Canada said Monday.

Gross domestic product growth was marginally below the consensus call of 4%, and also undershot the Bank of Canada's 4.2% forecast.

GDP...