** Hikma rises 6.7 pct after agreeing to buyBoehringer's specialty generics business for $2.65 bln in cash
** Valuation based on new Hikma shares priced at £23.50
** Best day for stock since January 2015
** Among top risers and most traded by average volumes onStoxx 600
(RM: alasdair.pal.thomsonreuters.com@reuters.net)