** Bavarian Nordic BAVA.CO shares rise 3.4%, boosted by its DKK 500 mln ($78 million) buyback plan, which broker Sydbank deems a "very positive signal" for investors

** The buyback, which overshadows short-term uncertainty, is the board's attempt to mend shareholder relations after the failed takeover bid from Nordic Capital, Permira, Sydbank says as it raises the stock to "buy" from "hold"

** The uncertainty stems from an information meeting planned for Dec. 11 where Bavarian plans to update on the state of the business

** Sydbank says the buyback reflects Bavaria's shift from a biotech to a pharma firm, citing acquisitions of travel vaccine portfolios from GSK and Emergent BioSolutions, combined with its core smallpox/mpox business

** The stock is one of the biggest gainers on STOXX 600 .STOXX index

($1 = 6.4344 Danish crowns)

(Reporting by Izabela Niemiec)

((izabela.niemiec@thomsonreuters.com))