Ukraine's Kyivstar gets 'outperform' rating as Oppenheimer starts coverage

** Oppenheimer initiates coverage on Ukrainian mobile operator Kyivstar with "outperform" rating

** Brokerage sets $20 PT, implying a near 70% upside to stock's last close

** Says KYIV has about 50% market share in wireless subscribers market despite low ARPU (average revenue per user), expects strong ARPU growth

** Digital services and fiber broadband, which currently add 11% and 5% respectively to revenue, can triple in the next seven years alongside a 10%-15% growth in revenue per year, brokerage says

** Post-war rebuild in Ukraine could add 200-400 basis points to KYIV's growth rate - Oppenheimer

** KYIV shares reversed premarket gains to fall 0.8% to $11.67

** Including session's move, KYIV down nearly 19% from its IPO last month