CANONSBURG, Pa. — A global pharmaceutical giant is poised for a growth spurt. A huge growth spurt.

Mylan NV, a $20 billion company, is merging with Upjohn, a division of Pfizer Inc., in an all-stock deal announced Monday morning. The merger will result in a new company, and is expected to take effect in or around mid-2020.

The boards of Mylan and Pfizer have unanimously approved the transaction, which also has to get a thumbs-up from Mylan shareholders. Pfizer shareholders will own 57 percent of the new company, which has yet to be named. Mylan shareholders will own 43 percent.

That new entity will offer a diverse portfolio of pharmaceuticals. Mylan is known for EpiPen and medications for the central nervous system, anesthesia, infectious disease and cardiovascular. Upjohn is Pfizer’s off-patent and generic business, whose medicines include Lipitor, Viagra and Celebrex.

Mylan has longtime ties to the region, operating from its global center in Southpointe near Canonsburg, and a manufacturing plant in Morgantown. Its headquarters are in the Netherlands, while Pfizer is based in New York City.

Headquarters for the new company has not been determined. Robert J. Coury, Mylan’s current chairman, will be executive chairman of the new firm.