Astrana set to open at lowest since April after unit hacked

** Shares of US physician-centric healthcare firm Astrana Health ASTH.O fall 8.4% to $32.15 premarket

** If losses hold, stock set to open at its lowest level since April

** Co discloses unauthorized access to confidential information in its unit, Astrana Health Management

** Threat actors impersonated co's personnel and contacted some employees to access information

** ASTH says hackers accessed certain confidential information

** Co says it currently does not expect the incident to have a material effect on its finances

** As of last close, ASTH stock up 41.5% YTD