A proposed merger between Pfizer and Allergan aims to create a pharmaceutical giant that would generate an estimated $64 billion in combined product sales and spend at least $1.6 billion on advertising.

The drugmakers on Monday announced the rumored $160 billion deal, stating that the boards of directors at both companies had unanimously approved the merger. The combined company will be named Pfizer plc and will maintain Allergan’s Irish tax domicile. It will be led by Pfizer CEO Ian Read. Allergan CEO Brent Saunders will take a seat on the board and will serve as president.

“Joining forces with Pfizer matches our leading products in seven high growth therapeutic areas and our robust R&D pipeline with Pfizer’s leading innovative and established businesses, vast global footprint and strength in discovery and development research to create a new biopharma leader,” Saunders said in a news release.

The reverse merger will also allow New York–based Pfizer to move its headquarters to Ireland in a so-called tax inversion. The US Treasury Department last week proposed new rules that seek to prevent such deals but analysts say those proposals shouldn’t hamper the deal.

“They don’t appear to have much relevance to the [Pfizer/Allergan] transaction given the ownership thresholds,” Tim Anderson, an analyst for Sanford C. Bernstein, said in a research note.

Like most other large pharmaceutical companies, Allergan and Pfizer have both grown significantly in size in recent years primarily through acquisition. Anderson said Pfizer has extensively relied on M&A to drive growth “because it has often lagged in R&D.”

In February Pfizer said it would purchase Hospira for $17 billion in a deal that gave it access to legacy injectables commonly used in hospitals as well as the Lake Forest, Ill.–based drugmaker’s biosimilars portfolio.

Pfizer reported $45.7 billion in revenue in 2014, according to securities filings. That year the drugmaker spent $8.4 billion on R&D and $14.09 billion on selling, information and administrative expenses. It spent $745.5 million on advertising in the first half of 2015 and $1.4 billion in 2014, according to Kantar Media.

Actavis in November of last year acquired Irvine, Calif.–based Allergan for $66 billion and then later renamed the Irish drugmaker Allergan. In 2014 the company spent $1.08 billion on R&D and $1.85 billion on selling and marketing. Its advertising spend in the first half of this year was $144.9 million, according to Kantar Media. It spent $266.8 million on advertising in 2014.

If the deal between Allergan and Pfizer goes through, the combined company is considering a long-awaited plan to split Pfizer’s new therapies business from its established product business. That decision would be made by the end of 2018, Pfizer said in the release.

About 35% of Allergan’s business stems from what it calls its North American brands, which is one of its three businesses that focuses on marketing new and innovative brand-name therapies.

The merger would allow Pfizer to further commercialize those brands in global markets, Pfizer’s executives said during a call with investors, according to Evercore ISI analysts.The deal is expected to provide those benefits as well as $2 billion in estimated operational synergies in the first three years of the deal closing. The transaction is expected to close in the first half of 2016.

Pfizer’s top-selling drugs in 2014 were antiepileptic drug Lyrica ($4.17 billion), the Prevnar vaccines ($4.46 billion) and Enbrel, a rheumatoid arthritis drug ($3.85 billion). Allergan’s top-performing drugs are the Namenda franchise ($899.3 million) and ulcerative colitis treatments Delzicol and Asacol ($564 million). Its dermatology and established brands business, which includes Botox, brought in $755.4 million in sales in 2014.