Pfizer has an enterprise value of $221 billion.

Allergan has an enterprise value of $160 billion.

The two companies combined would have a joint EV of nearly $400 billion and a market cap of well over $300 billion. That would make a potential merger between the two the largest M&A deal in history, while a “mere takeover” of Allergan by Pfizer would still rank it as the fourth largest deal in history and the largest deal in a year that is shaping up as a record for M&A.

And, according to the WSJ, such a deal may be just a few months if not weeks away. To wit:

Drug makers Pfizer Inc. and Allergan PLC are considering combining, in what would be a blockbuster merger capping off a torrid stretch for health care and other takeovers.

Pfizer recently approached Allergan about a deal, according to people familiar with the matter, with one of them adding that the process is early and may not yield an agreement. Other details of the talks are unclear.

Allergan currently has a market capitalization of $112.5 billion, meaning that a deal for the company could be the biggest announced takeover in a year that is already on pace to be the busiest ever for mergers and acquisitions.

Granted, this won’t be the first time the two pharmaceutical behemoths have been said to consider merging, although it would be the first time for Allegan in its current iteration which is a combination of Forest Labs, Watson, Warner Chilcott, Actavis and, of course Alergan; furthermore this time may be also different when one considers the recent last gasp surge in deal announcements, which is nothing more than an attempt by companies to lock in their near all time high stock prices as a merger currency, while debt is still debt.

Will the deal pass regulatory scrutiny? If enough palms are greased, sure.

More complex would be the whole tax-avoidance issue: “A tie-up with Allergan could also be a way for New York-based Pfizer to lower its corporate tax rate. Allergan is based in Dublin, which has a significantly lower tax rate than the U.S.”