Updates

** Shares of health insurer UnitedHealth Group UNH.N fall 14.7% to over four-year low of $324.03

** CEO Andrew Witty decides to step down for personal reasons

** Former CEO Stephen Hemsley returns to the top role after stepping down in 2017

** "We believe the move should be welcome by the Street given the success that Hemsley had in his long run as CEO. It is unclear whether this is a role he wants to remain in long term or just until UNH emerges from these challenges" - brokerage Oppenheimer

** Co also suspends 2025 outlook as medical expenditures expected to be higher than anticipated

** Co says on investor call that it was seeing more demand for medical care from new members and from people with complex conditions, increasing costs

** UNH expects to return to growth in 2026, co says

** Including session's moves, UNH down 35.5% YTD

(Reporting by Sneha S K and Siddhi Mahatole)

((Sneha.SK@thomsonreuters.com))