** Pivotal Research upgrades data storage equipment maker (NTAP.O) to "buy" from "hold," on higher growth expectations

** Expects management to announce a minimum of $2.5 bln multi-year buyback and dividend hike of 50-100 pct from current levels at analyst meeting - Pivotal analyst Lou Miscioscia

** Stock up 46 pct in last 12 months

** Pivotal hikes PT by $10 to $72, a potential 19 pct upside to Tuesday's close; median PT $64

** NTAP is expected to host its 2018 financial analyst day on April 5

** Current average rating on shares is "buy"; 15 of 29 brokerages rate the stock "buy" or higher, 13 "hold" and 1 "sell"

** Brokerage raises its 2019 EPS forecast to $3.90 from $3.72; analysts currently estimate EPS of $3.77, per TR data