** Shares of diagnostics co Veracyte VCYT.O climb 6.6% to $25.2 premarket
** VCYT to replace Aero parts maker Triumph Group in S&P 600 Small Cap Index .SPCY, S&P Dow Jones Indices says
** Change will take effect before markets open on July 29
** J.P.Morgan analysts estimate S&P 600 indexer demand for VCYT shares to be 8.5 mln
** Stephens analysts expect passive funds will need to purchase 10.4 mln VCYT shares, which implies ten days of buying demand
** Investment firms Warburg Pincus and Berkshire Partners completed the acquisition of Triumph Group on July 24
** The take-private $3 bln deal was first announced on Feb 3
** As of last close, VCYT shares down more than 40% YTD
(Reporting by Shashwat Chauhan in Bengaluru)
((Shashwat.Chauhan@thomsonreuters.com))