The markets opened lower with the Dow falling 36 points to 17,565 as investors monitored global events. Nasdaq lost 7 points to 4,787.

On the upside

Valeant Pharmaceuticals (NYSE: VRX) chief executive Michael Pearson will leave the company and activist investor Bill Ackman will join the company's board.

Sherwin-Williams (NYSE: SHW) will pay a premium of approximately $11.3 billion in cash to acquire Valspar (NYSE: VAL).

Bargain hunters continued to snap up shares of Oncothyreon (Nasdaq: ONTY).

On the downside

Affymetrix (Nasdaq: AFFX) rejected a $1.5 billion acquisition offer from Origin Technologies.

Trinseo (NYSE: TSE) announced a secondary offering of 9.6 million common shares.

Shares of Whiting Petroleum (NYSE: WLL) continued to fall.

In the broad market, advancing issues outpaced decliners by a margin of 5 to 4 on the NYSE and by 7 to 5 on Nasdaq. The broader S&P 500 lost 4 points to 2,045. Bitcoin lost $2 to $410.