** Shares of low-cost carrier Sun Country Airlines SNCY.O down 5.9% at $9.29 on Thurs as its finance chief leaves to take the reins at struggling rival Spirit Airlines SAVEQ.PK

** SNCY shares slumped as much as 9.5% early Thurs to record low of $8.93

** Spirit on Thurs appointed Dave Davis as new CEO, beginning on Mon, weeks after emerging from bankruptcy and reconstituting its board

** Sun Country in a regulatory filing on Thurs announced Davis' departure, saying expects to start formal search process for a permanent replacement

** Co's board appointed Bill Trousdale as interim CFO. Trousdale has served as co's VP of financial planning and treasurer since 2018

** Also, co said Gregory Mays is stepping down from his role as COO, but will remain an employee for a mutually agreed timeframe to assist with transition of his duties

** Mays' resignation not a result of any disagreement with co or the board, it said in the filing

** In Feb, private equity sponsor Apollo Global Management APO.N divested its remaining 12% stake in SNCY via ~6.3 mln share secondary offering

** APO acquired co in 2017 and took SNCY public in 2021 IPO priced at $24

** With move on Thurs, SNCY shares down 36% YTD

** Avg rating among 9 analysts is "buy" and median PT is $16, LSEG data shows

(Lance Tupper is a Reuters market analyst. The views expressed are his own)

((lance.tupper@tr.com 1-646-279-6380))