** Shares of Palantir Technologies PLTR.N drop 2.7% to $17.8 premarket

** Japan's Sompo Holdings 8630.T sells part of its stake in data analytics firm

** Spokesperson for Japanese insurer says stake sale was for undisclosed amount, but Sompo booked profit of 86 bln yen ($584.20 mln)

** They did not disclose details on Sompo's remaining stake in PLTR

** Palantir in Feb signed $50 mln expansion agreement with Sompo, which is also Palantir's customer

** Insurer had invested $500 mln in Palantir in June 2020, a few months before U.S. firm went public

** In 2019, Palantir launched 50-50 JV with Sompo called Palantir Technologies Japan K.K. to service the Japanese government as well as commercial clients

** As of Tuesday's close, PLTR nearly tripled in value this year

($1 = 147.2100 yen)

(Reporting by Pavithra S and Pushkala Aripaka in Bengaluru)

((pavithra.s@thomsonreuters.com))