Apple is also widely believed to be working on bigger-screen smartphones, Samsung's mainstay products.

Dainippon's four mainstay products have patents that have either expired or will expire shortly.

Drug companies are increasingly looking to shed smaller divisions they view as non-core so they can better focus on their mainstay products.

Murata's mainstay products are ceramic capacitors, tiny parts that control the flow of electricity in electronic devices from game consoles to car engine controls.

The sale processes underscore efforts by large drugmakers to shed smaller divisions they view as non-core so they can better focus on their mainstay products.