The activist says he has recently purchased a large stake in Allergan, which in April called off its $150 billion pact with Pfizer.
Billionaire Bill Ackman's recent appointment to the troubled drugmaker's board could signal a meanful change of direction.
Jim Cramer says the antitrust environment out there will make it difficult for any railroad mergers to be approved by regulators.
Investors are gearing up for another assessment of the global economy, as the Fed Prepares to release the minutes of its March meeting.
The latest rules are seen likely to prompt a rethink of the $150 billion pharmaceuticals deal.