After a 2 day decline the bulls fought back today fueling a sharp rally with stocks closing at session highs. The Dow 30 gained 113 (0.65%), the S&P 500 added 21 (1.05%), and the Nasdaq 100, which was supported by the biotech sector gained 76 (1.59%).Allergan (AGN  ) and Pfizer (PFE  ) take over the headlines today as Pfizer said it will terminate its planned $160 billion takeover of Allergan. The decision comes after the U.S. Department of Treasury issued new rules to curb tax inversions. Allergan finished up 3.46% today and Pfizer gained 5.01%.

Halliburton (HAL  ) shares climbed 5.93% despite the news that the U.S. Department of Justice has filed a lawsuit to stop Halliburton from acquiring rival Baker Hughes (BHI  ). In a statement, the DOJ said that the merger would "eliminate significant head-to-head competition in the oilfield services industry."

Apple (AAPL  ) adds 1.05% to its recent rally as Needham initiated coverage on the stock with a strong buy and a price target of $180 per share. Analyst Laura Martin cited higher pricing power and more predictable revenue streams as catalysts for Apple's stock.

Shares of Polycom (PLCM  ) surged 8.03% on reports that it is in advanced merger talks with Mitel Networks (MITL  ). A deal could be announced as soon as this week.

Lastly, Cree (CREE  ),  the manufacturer of LED applications lost 14.60% today as the company announced that it anticipates lower-than-expected quarterly results. Cree said its third-quarter revenue will miss estimates due to issues including product delays.