** Shares of British building materials supplier SIG PLC SHI.L down 3.4% at 14p, among top losers on FTSE midcap .FTMC index
** Co remains cautious on H2 market improvement, having seen no notable demand increase in H1
** Co appoints Pim Vervaat as CEO
** Co expects FY underlying operating profit in line with market consensus of 31.6 million pounds ($43.06 million), as per a company poll
** SHI down ~12% YTD
($1 = 0.7338 pounds)
(Reporting by Nithyashree R B in Bengaluru)
((NithyashreeRB@thomsonreuters.com))