Pfizer And Allergan Merger Ranks As Biggest-Ever Pharmaceutical Deal

The blistering pace of pharmaceutical merger and acquisition activity is only heating up as drugmakers seek to shift their headquarters to low tax jurisdictions, and take up business models that prioritize efficiency over gross R&D spending. On Monday, Pfizer and Allergan unveiled an all-stock merger that will allow the combined company, Pfizer PLC, to move its headquarters to Ireland and focus on corporate cost cuts.

The stock deal, which values Allergan at $363.63 a share, or 11.3 shares in the merged company, Pfizer PLC, is the largest merger in the pharmaceutical sector on record. It is expected to create a biopharma juggernaut with the financial flexibility to make new investments, while also increasing profitability and returns of capital to investors.

Although Monday's deal is a seminal moment in the reinvention of a leaner and more shareholder oriented pharmaceutical industry, it may do little to slow a tide of corporate shape-shifting.

In fact, the all-stock nature of the merger also gives Pfizer PLC the leeway to continue considering a separation into two companies, something current CEO Ian Read has been contemplating for years. Were a split to occur in a few years time, it might give new legs to today's pharma M&A boom. With Allergan and Pfizer ranking as the biggest-ever pharma merger, here's a list of the industry's seven larges deals, per Bloomberg  data.

1. Allergan announces merger with Pfizer in an all-stock deal valued at $160 billion
2. Pfizer acquires Warner-Lambert in 1999 in an all-stock deal valued at 87.3 billion
3. Sanofi buys Aventis SA for $73.5 billion in 2004 in a cash and stock deal
4. Glaxo acquires SmithKline Beechan for $72.4 billion in stock in early 2000
5. Allergan acquires Actavis for $65 billion, in a cash and stock merger that closed in 2015
6. Pfizer acquires Pharmacia corp for $64.3 billion in stock in 2002
7. Pfizer acquires Wyeth for $64.2 billion in cash and stock in 2009