Boeing shares dropped nearly 5% in premarket trading Monday after South Korea ordered inspections of all B737-800 planes following a deadly Jeju Air crash over the weekend. The crash killed nearly all passengers onboard. South Korea's Ministry of Land, Infrastructure, and Transport has launched a "comprehensive special inspection" of the aircraft model. The U.S. National Transportation Safety Board leads an investigation team to assist South Korea's probe. Boeing expressed condolences and pledged support to Jeju Air and the crash victims' families.