** Shares of payments firm Shift4 Payments FOUR.N rise 1.3% to $101.23 in premarket trading

** FOUR shares slumped 12.4% on Wednesday after U.S. President-elect Donald Trump picked FOUR CEO Jared Isaacman to head NASA

** Wall Street analysts view Isaacman's pending exit as representing the realization of the key person risk

** Benchmark says Isaacman's departure has given rise to significant uncertainty over the company's ability to execute its strategy as effectively as it has up to this point

** Key person risk has been one of FOUR's primary vulnerabilities since it went public in 2020 - Benchmark

** Brokerage downgrades its recommendation on FOUR to "hold" from "buy" and removes $99 PT, as it believes stock is likely entering range-bound period given uncertainty arising from departure

** As of last close, FOUR shares up 34.5% YTD

(Reporting by Arasu Kannagi Basil in Bengaluru)

((ArasuKannagi.Basil@thomsonreuters.com;))