Companies in the news:Air Canada (TSX:AC). Down $1.13 or 2.52 per cent to $43.62. Air Canada is challenging WestJet Airlines Ltd.’s $3.5-billion acquisition by Onex Corp., arguing in a filing to the country’s transportation regulator the deal breaches federal rules that limit foreign ownership of carriers. Air Canada said in a letter to the Canadian Transportation Agency that co-investors in Kestrel Bidco Inc. — the Onex subsidiary that is buying WestJet — may come from outside the country, amounting to a “serious risk” — though some experts view the filing as a delay tactic as the country’s biggest airline grapples with its own regulatory gauntlet in a deal to acquire travel company Transat A.T. Inc.TC Transcontinental (TSX:TCL.A). Up three cents, or 0.21 per cent, to $14.11. TC Transcontinental has agreed to sell the building that housed its former printing operations in Fremont, Calif., for US$75 million, with the proceeds to be used to reduce debt, the company said Tuesday. The buyer is Hearst Corp., which took over printing operations at the plant in April 2018 as the two companies dissolved a multi-year outsourcing agreement in which Transcontinental printed the San Francisco Chronicle for the media company. It announced separately that it has invested an undisclosed amount to buy a 60 per cent interest in Trilex, a plastic packaging supplier in Ecuador — its eighth packaging acquisition since 2014. The Canadian Press TORONTO — Some of the most active companies traded Tuesday on the Toronto Stock Exchange:Toronto Stock Exchange (16,399.23, down 42.84 points).Encana Corp. (TSX:ECA). Energy. Down eight cents, or 1.36 per cent, to $5.82 on 12.9 million shares.Crescent Point Energy Corp. (TSX:CPG). Energy. Up 27 cents, or 6.43 per cent, to $4.47 on 7 million shares.Enbridge Inc. (TSX:ENB). Energy. Up seven cents, or 0.16 per cent, to $44.60 on 5.7 million shares.Kinross Gold Corp. (TSX:K). Up 31 cents, or 4.68 per cent, to $6.93 on 5.3 million shares.Bombardier Inc. (TSX:BBD.B). Industrials. Up eight cents, or 4.65 per cent, to $1.80 on 4.9 million shares.Barrick Gold Corp. (TSX:ABX). Materials. Up 13 cents, or 0.5 per cent, to $25.94 on 4.6 million shares.