** Shares of life insurer NobleOak NOL.AX rise as much as 11.5%, their highest one-day pct gain since May 2023, to A$1.65

** Co's first-half in-force premium rises 20% to A$422.9 million ($263.55 million); underlying NPAT jumps 11%

** Co's earnings gain on improved margins driven by conservative risk retention strategy and portfolio mix

** Shares up 1.3% this year

($1 = 1.6046 Australian dollars)

(Reporting by Nichiket Sunil in Bengaluru)

((Nichiket.Sunil@thomsonreuters.com;))