Some of the most active companies traded Monday on the Toronto Stock Exchange:

Toronto Stock Exchange (15,052.03, down 3.96 points):

Polaris Materials Corp. (TSX:PLS). Building Materials. Up $1.74, or 181.25 per cent, to $2.70 on 7.5 million shares.

Hydro One Ltd. Instalment Receipts (TSX:H.IR). Utilities. Up 35 cents, or 0.92 per cent, to $38.25 on 4.5 million shares.

Trevali Mining Corp. (TSX:TV). Miner. Up four cents, or 2.82 per cent, to $1.46 on 4.05 million shares.

Yamana Gold Inc. (TSX:YRI). Miner. Up 19 cents, or 5.54 per cent, to $3.62 on 3.8 million shares.

Baytex Energy Corp. (TSX:BTE). Oil and gas. Down 13 cents, or 4.23 per cent, to $2.94 on 3.8 million shares.

Lundin Mining Corp. (TSX:LUN). Miner. Up 51 cents, or 5.49 per cent, to $9.80 on 3.7 million shares.

Companies reporting major news:

Toromont Industries Ltd. (TSX:TIH). Industrials. Up $4.97, or 11.07 per cent, to $49.87 on 1.4 million shares. The industrial equipment company has a friendly deal to buy the Quebec-based Hewitt Group for a combination of cash and shares worth about $1.02 billion.