Gelteq (GELS) shares were down 33% in premarket activity Friday, following a 197% gain in the previous session.

Sensus Healthcare (SRTS) stock was down 26% after closing Thursday with a 3.9% decline.

Pop Culture Group (CPOP) shares were 20% lower, following a 31% loss in the prior session.

Smith Micro Software (SMSI) shares were down 20%, following a 27% gain Thursday.

Sleep Number (SNBR) stock was down 19% after the company agreed to combine with Sleep Country Canada under an asset purchase agreement and launched a voluntary Chapter 11 sale process to facilitate the transaction.