Boeing stock fell more than 5% early Monday after a Jeju Air flight carrying 181 passengers and crew traveling from Thailand to South Korea crashed on landing Sunday, killing 179. This is what investors need to know.

On Sunday, a Jeju Air plane traveling from Bangkok's Suvarnabhumi International Airport crashed at a South Korean airport, killing 179 people. It was carrying 181 passengers and crew members. Jeju Air's stock slumped as much as 16% and closed 8.7% lower on Monday.

Boeing stock (BA) closed down 2.3% on Monday as investigators looked into the crash of a South Korean Boeing jet. On Sunday, a Jeju Air Boeing 737-800 crash-landed at Muan International Airport in South Korea.