Dropbox falls after Citi downgrade on growth concerns
** Shares of cloud platform provider Dropbox DBX.O fall 5% to $32.5 premarket
** Brokerage Citi downgrades the stock to "sell" from "neutral"
** Citi says recent gains have outpaced the company's underlying business progress and growth prospects
** Co's core business remains under pressure and has yet to show sustained growth despite recent stabilization - Citi
** One of nine brokerages rates the stock "buy", four "hold" and four "sell" or lower; median PT is $29 - data compiled by LSEG
** As of last close, stock up 23.1% YTD