Allergan Inc got US$9.6 billion cheaper for investors who were interested in acquiring the Botox wrinkle treatment.

Since April, Allergan's market value plunged 28% to US$25 billion. Venture capitalists became worried that the generic rivalry to its Restasis eye drops including drug studies that were behind the schedule would interfere with the future sales progress.

Despite the delay, Allergan's development prospects from Botox and other medical products were expected to attract investors. GlaxoSmithKline Plc and Merck & Co. were just some of the interested buyers, according to Bank of Montreal.

Botox sales were expected to increase to US$3 billion in 2017, up 67% from 2012, as reported by data compiled by Bloomberg.

Leerink Swann LLC said Nestle SA could team up its skin-care business with Allergan. It added that Allergan was expected to sell its stocks for US$116 each.

"If you're large pharma and you're looking for steady, growing franchises, Allergan has several of them," a New York-based analyst at BMO, David Maris, said in an interview on the phone. "You've had a series of disappointments, but I think the market has overreacted. Botox is the crown jewel, and I could see Allergan fitting well with a number of companies."