** Retirement and life insurance products provider Corebridge Financial's CRBG.N shares jump 5.1% to $33.15 in extended trading

** CRBG will join the S&P MidCap 400 .IDX prior to market open on December 17, S&P Dow Jones Indices announces

** Co will replace energy firm Allete ALE.N, which is set to be acquired by Canada Pension Plan Investment Board and Global Infrastructure Partners

** S&P MidCap 400 is a benchmark for mid-sized companies

** 10 of 15 brokerages rate the stock "buy" or higher and five "hold"; median PT $23.50 — data compiled by LSEG

** As of last close, CRBG stock up 5.4% YTD

(Reporting by Arasu Kannagi Basil in Bengaluru)

((ArasuKannagi.Basil@thomsonreuters.com))