** Challenger CGF.AX falls as much as 4.8% to A$8.020, lowest since July 29

** Investment management co posts H1 normalised net profit after tax of A$229 mln ($161.6 mln), below Citi's consensus estimate of A$233 mln

** Citi says profit miss due to tighter credit spreads driving significantly lower investment yields in H1, along with stronger transaction, placement fees

** Notes HY total life gross sales rose 11% y/y, while life book grew 5.8% y/y; but says sales mix appears lower quality with higher skew to shorter duration fixed term sales

** Adds co's announced buyback of upto A$150 mln is a "positive surprise" and symbolic of co's future capital return potential

** Co reaffirms previous FY26 guidance of normalised NPAT of A$455 mln-A$495 mln

** CGF down 12.6% YTD

($1 = A$1.4168)

(Reporting by Shruti Agarwal in Bengaluru)

((Shruti.Agarwal@thomsonreuters.com))