** Senior healthcare provider Alignment Healthcare ALHC.O shares up 4.9% premarket to $18 as co set to join S&P SmallCap index .SPCY later this week
** ALHC to replace Sun Country Airlines SNCY.O in SPCY prior to market open on Thurs, May 14, S&P Dow Jones Indices announced late Mon
** Sun Country being acquired by Allegiant Travel ALGT.O in $1.5 bln deal
** Stephens analyst Melissa Roberts said in a note she expects passive funds will need to purchase 21.5 mln ALHC shares which implies about 6 days of buying demand
** Orange, California-based ALHC has ~206.7 mln shares outstanding for about $3.5 bln market cap
** Stock down 13% YTD at close on Mon
** 12 of 14 analysts rate the stock "strong buy" or "buy", 2 "hold"; median PT $25, per LSEG data
(Lance Tupper is a Reuters market analyst. The views expressed are his own)
((lance.tupper@thomsonreuters.com))