Stock assets owned by Samsung Electronics vice chairman Lee Jae-yong suffered the biggest decline among the country’s 50 richest people this year, according to Seoul-based corporate tracker Chaebul.com.

Lee‘s stock assets were worth 6.39 trillion won as of this month, down about 20 percent from 7.61 trillion won in January. The sluggish performance of major Samsung affiliates was the primary cause of the fall.

The stock assets of Lee’s two sisters -- Boo-jin, CEO of Hotel Shilla and Seo-hyeon, CEO of Samsung C&T -- also slipped during the same period. The wealth lost by these three siblings was estimated at 2.17 trillion won, accounting for 82 percent of the total decline of the group, Chaebul.com said.

In contrast, their father Lee Kun-hee’s net asset value grew 710.5 billion won, or 6.3 percent. He remained Korea’s richest person in terms of stock assets.