South Korea's biggest automotive giant is losing ground in its own home country.

At one time, the Hyundai-Kia Automotive Group produced four out of five vehicles running in South Korea.

It's still the number one car company, but now its combined domestic market share has dropped to an all-time low of just under 60 percent.

Last month, Hyundai Motor had a 31-point-nine percent share while Kia Motors had 27 percent, for a combined share of 58-point-nine percent. 

More imported vehicles and disrupted production due to labor strikes are some of the key reasons cited for the drop.

In second place behind Hyundai-Kia in terms of the domestic market is GM Korea, the South Korean unit of General Motors, with an eleven-point-three percent share.  Renault Samsung comes in third with nine percent and Ssangyong Motor is fourth with six-point-four percent.

All other foreign car brands combined make up 13-point-nine percent of South Korea's domestic market.