Why do employees hold their vested stocks while they can sell them?

NIEN-CHI LIULin, A.A.LinLin, C.-H.C.-H.Lin2020-12-162020-12-162009https://www.scopus.com/inward/record.uri?eid=2-s2.0-59249108514&doi=10.1080%2f09585190802528532&partnerID=40&md5=b539a16627f31f16dfc8484126f8368bhttps://scholars.lib.ntu.edu.tw/handle/123456789/526223Why do employees hold their vested stocks while they can sell them?journal article10.1080/095851908025285322-s2.0-59249108514