Most actively traded companies on the TSX

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

Toronto Stock Exchange (13,704.19, down 137.73 points):

Niko Resources Ltd. (TSX:NKO). Oil and gas. Down four cents, or 26.67 per cent, to 11 cents on 7.3 million shares.

Concordia Healthcare Corp. (TSX:CXR). Health-care. Down $4.83, or 13.67 per cent, to $30.50 on 5.5 million shares.

Barrick Gold Corp. (TSX:ABX). Miner. Down 42 cents, or 4.09 per cent, to $9.84 on 5.1 million shares.

Yamana Gold Inc. (TSX:YRI). Miner. Down 17 cents, or 5.17 per cent, to $3.12 on five million shares.

Encana Corp. (TSX:ECA). Oil and gas. Down 33 cents, or three per cent, to $10.67 on 4.1 million shares.

Baytex Energy Corp. (TSX:BTE). Oil and gas. Down one cent, or 0.18 per cent, to $5.49 on 3.9 million shares.

Companies reporting major news:

Valeant Pharmaceuticals International Inc. (TSX:VRX). Drugs, health-care products. Down $36.64, or 19.20 per cent, to $154.21 on 3.1 million shares. Trading in Valeant shares was briefly halted after short-seller research firm Citron Research compared the Canadian pharmaceutical company to the collapsed energy giant Enron and accused it of creating a network of phantom pharmacies to fool auditors. The drug company denied the allegations.

today on the Toronto Stock Exchange as its stock fell 30 per cent in morning trading. The Quebec-based company saw its shares plummet to just below $117 at one point, setting a new 52-week low. It has been under a considerable degree of political and legal scrutiny in the United States over increases to some drug prices.