** Shares of cruise operator Viking Holdings VIK.N fall nearly 3% to $57.5 in premarket trading

** Brokerage Mizuho initiates coverage on stock with "underperform" rating and a PT of $54, which implies an 8.8% downside on stock's last close

** While VIK has a unique business model and a strong management team, this is largely priced in, brokerage says

** Mizuho does not see earnings/multiple catalyst path that will lead to company's re-rating from here

** Brokerage sees the risk of incremental competition on the business as Royal Caribbean's RCL.N Celebrity cruises capacity could equate to 20% of company's River business in 5 years

** 12 of 18 brokerages rate the stock "buy" or higher, five "hold" and one "sell"; median PT is $63 - data compiled by LSEG

** As of last close, VIK shares up about 34.4% YTD

(Reporting by Parth Chandna)

((Parth.Chandna@thomsonreuters.com;))