Mannatech (MTEX) shares were down 17% pre-bell Friday, adding to Thursday's losses.
Contineum Therapeutics (CTNM) shares fell 16% following a muted session.
Curbline Properties (CURB) shares dropped 15% after closing nearly flat on Thursday.
Addex Therapeutics (ADXN) shares retreated 15% following a 1.1% loss in the previous session.