** Cybersecurity firm F5's FFIV.O shares rise 3.9% to $277.84 premarket

** JP Morgan upgrades to "overweight" from "neutral"

** Raises PT to $345 from $295, an upside of ~29% to stock's last close

** Average rating of 14 analysts is "hold"; median PT is $295 - data compiled by LSEG

** In 2025, stock rose 1.5%

(Reporting by Anhata Rooprai in Bengaluru)

((Anhata.Rooprai@thomsonreuters.com))