** Semiconductor packaging and test services firm Amkor Technology's AMKR.O shares down 5% premarket to $49 after secondary offering priced

** Tempe, Arizona-based AMKR late Thurs announced investment vehicle for members of the Kim Family offloaded 10 mln shares at $48.75 for $487.5 mln gross proceeds

** Offering price represents 5.5% discount to stock's last close

** Post-offering, Kim Family to own >49% of AMKR's stock; selling stockholder entered into 180-day lockup agreement on its remaining holdings

** AMKR has ~247.3 mln shares outstanding as of Feb 10, per the offering prospectus

** Goldman Sachs sole bookrunner

** AMKR shares on Thurs fell 8%, reducing YTD gain to 31%. Stock closed at $22.19 a year ago

** Of 12 analysts, recommendation breakdown is 4 "buy", 7 "hold", 1 "sell"; median PT of $55 up from $35 a month ago, per LSEG data

(Lance Tupper is a Reuters market analyst. The views expressed are his own)

((lance.tupper@tr.com 1-646-279-6380))