The U.S. energy company acquired shares in Cenovus in 2017 when the Calgary-based company bought some oilsands operations and natural gas assets from ConocoPhillips.
Cenovus paid $17.7 billion in that deal, including $14.1 billion in cash and 208 million shares.
ConocoPhillips announced the plan to sell the shares as it reported its first-quarter results. It says it plans to sell the shares in the open market beginning in the second quarter of 2021 and expects to complete the sales by the fourth quarter of 2022.
It says the pace of the sales will be guided by market conditions.
Cenovus shares were down 42 cents or about four per cent at $9.49 in mid-morning trading on the Toronto Stock Exchange.