Biotechnology company Amylin Pharmaceuticals has drawn initial bids from drugmakers Merck & Co and Sanofi, Bloomberg News reported on Friday, citing anonymous sources.

The drugmakers made offers of at least $25 a share, which would value Amylin at more than $4 billion, the report said.

Sources have told Reuters that Amylin, which sells the diabetes drugs Byetta and Bydureon, started reaching out to potential buyers in April.

Merck declined to comment. Amylin and Sanofi were not immediately available to comment.