Oct 15 (Reuters) - ** Shares of British gambling firm Entain ENT.L fall 3% to 814 pence, biggest loser on FTSE 100 index .FTSE, which is up 0.1%
** Co posts 7% rise in Q3 net gaming revenue (NGR) at constant currency (CC), slowing from 10% growth in first half, with roughly 1-2 percentage points' impact from customer-friendly sports results in September
** Reiterates annual outlook for about 7% online NGR growth on CC basis and core profit of between 1.1 billion pounds and 1.15 billion pounds ($1.47 billion- $1.54 billion)
** Smaller peer Rank Group RNK.L posts 9% rise in like-for-like NGR for its first-quarter
** As of last close, stock up 22.2% YTD, while .FTSE up 15.7%
($1 = 0.7488 pounds)
(Reporting by DhanushVignesh Babu in Bengaluru)
((DhanushVignesh.Babu@thomsonreuters.com))