** Shares of utility Vistra Corp VST.N up 4% to $159.2 premarket

** Jefferies upgrades rating to "buy" from "hold"; raises PT to $203 from $191

** New PT is a ~33% upside to stock's last close

** Brokerage argues the stock is underpricing upside from future data center deals

** The brokerage expects 2026 to be a turning point in resolving PJM's structural imbalance, but it still sees significant uncertainty around PJM backstop procurement

** "We believe there will be significantly fewer data center contracts on existing assets today but the 'base' valuation represents a buying opportunity"- brokerage

** 19 of 20 brokerages rate stock "buy" or higher, and 1 "hold" - data compiled by LSEG

** In 2025, VST gained 17%

(Reporting by Dharna Bafna in Bengaluru)

((Dharna.bafna@thomsonreuters.com))