** British supermarket chain Sainsbury's SBRY.L down 5.1% at 312.2p; top loser on FTSE 100 index .FTSE
** Maintains FY retail underlying operating profit forecast of more than 1 billion pounds ($1.34 billion)
** Posts 3.4% rise in underlying sales for Christmas quarter while sales at Argos, co's multi-category retailer, falls 1%
** General merchandise and clothing sales in SBRY's stores falls 1.1% in Q3
** In 2025, SBRY shares gained 22.8%
($1 = 0.7448 pounds)
(Reporting by Atharva Singh in Bengaluru)
((Atharva.singh@thomsonreuters.com))