** Advertising firm Omnicom's OMC.N shares rise 5.8% to $74.23 in afternoon trading

** UBS raises PT to $108 from $99, representing an upside of 53.9% to the stock's last close

** Brokerage believes OMC could announce a buyback program of less than $3 billion over 2026 and 2027

** UBS upgrades forecast to include IPG, and assumes OMC will classify 5% of revenues as "held for sale"

** Average rating of 12 analysts is "buy", their median PT is $103 — data compiled by LSEG

** Up to last close, stock has fallen 18.4% this year

(Reporting by Anhata Rooprai in Bengaluru)

((Anhata.Rooprai@thomsonreuters.com))