** Refiner Vertex Energy's shares VTNR.O fall 5.77% to
$3.43
** Brokerage Stifel downgrades co's rating to "hold" from
"buy", cuts PT to $4 from $6
** Stifel says weak crack spreads in refining and renewable
diesel segments will limit valuation upside over 12 months
** "Conversion to lower cost feedstock is a possible
long-term solution to poor subsidy values but that does not
happen quickly," says brokerage
** The new price target represents a 9.89% upside to the
stock's last close
** 3 of 7 brokerages rate the stock "buy" and 4 "hold";
their median PT is $6.75 - LSEG
** Including session's losses, stock has fallen 44.68% YTD
(Reporting by Kabir Dweit)
((Kabir.Dweit@thomsonreuters.com))