Jefferies downgrades Roblox to 'underperform'; shares fall 1.5%      

** Shares of gaming platform Roblox RBLX.N fall nearly 1.5% to $44.95 premarket

** Jefferies downgrades stock rating to "underperform" from "hold"

** Says, "While we are positive on RBLX's focus on expanding its platform to support new genres and the 18+ age demo, we believe the improvement in US & Canada user and Bookings growth will be longer and more costly than the market expects"

** Recent viral games such as Steal an Egg are unlikely to bring incremental audiences to the platform, adds Jefferies

** 38 analysts rate stock "hold" on average; median PT is $47 - data compiled by LSEG

** Up to last day's close, the stock had fallen ~43% YTD