Shares of Allergan jumped 15 percent in premarket trading Thursday on reports that a deal may be in the works with Pfizer Inc., which would be just the latest in a string of massive pharmaceutical mergers.

A deal between the pharmaceutical companies, as reported by the Wall Street Journal, would create a massive drug development company with treatments for a wide range of conditions ranging from high cholesterol to erectile dysfunction.

Citi analyst Liav Abraham pointed out that Pfizer executives have talked openly about a corporate inversion, a maneuver in which a U.S. company reincorporates in another country by acquiring another company there to take advantage of lower tax rates.

Allergan, based in Dublin, would be among Pfizer’s most likely targets, Abraham said.

Inversions have become a hot political topic, raising the ire of lawmakers in Washington, and the subject came up in Wednesday’s Republican presidential debate.

Last week, billionaire Carl Icahn said that he was setting up a $150 million super PAC bent on revising U.S. corporate tax law and ending the practice of inversions.

Allergan PLC is best known for its wrinkle treatment Botox. In March, Ireland-based Actavis closed its $66 billion buyout of the company and changed its corporate name to Allergan. In July, the company agreed to sell its generic business to Teva Pharmaceutical Industries Ltd. for about $40 billion.

Allergan stock rose $42.80 to $330.01 before the start of regular trading.