Complex sentence: In 2016, G-Dragon started endorsing Shinsegae, the largest retailer in South Korea and his merchandises were reported to take up over 49% of sales in the YG store.
Split into simpler sentences: In 2016, G-Dragon started endorsing Shinsegae, the largest retailer in South Korea. His merchandises were reported to take up over 49% of sales in the YG store.