SEOUL (Reuters) - Hyundai Motor Co 005380.KS shares gained the most in over five-and-a-half years on Tuesday on speculation that its parent group, controlled by Chairman Chung Mong-koo, will reorganize its ownership structure.

FILE PHOTO - Hyundai vehicles are lined up in the company's presentation area during the North American International Auto Show in Detroit, Michigan, U.S., January 10, 2017. REUTERS/Mark Blinch/File Photo

Hyundai Motor Group may join Samsung Group and possibly other family-owned conglomerates to adopt a holding company structure as politicians call for reform following a graft scandal involving President Park Geun-hye, analysts said.

Samsung Group chief Jay Y. Lee has been on a trial since being arrested for his alleged role in the scandal that led to the removal from office of Park earlier this month.

Also on Tuesday was market speculation that U.S. activist hedge fund Elliott Management Corp, which had pressured Samsung Electronics Co Ltd 005930.KS to restructure and boost dividends, may have bought a share in Hyundai Motor, analysts said.

But a person familiar with the matter told Reuters, without elaborating, that the rumors were groundless. Hyundai Motor said it does not comment on market speculation.

“The company is part of a particularly complex and suboptimal capital and corporate structure, and we see significant value that can be unlocked from restructuring,” Goldman Sachs said in a report on Hyundai Motor on Monday.

“In contrast to the consensus view that Hyundai Mobis would become the ultimate holding company, we see Hyundai Motor as the nexus for restructuring,” the bank said.

Hyundai Motor shares ended up 8.6 percent, its biggest daily gain since August 2011. Affiliate Kia Motors Corp 000270.KS rose 3.5 percent and Hyundai Mobis Co Ltd 012330.KS climbed 3.1 percent.

Parliament and presidential hopefuls are pushing to empower institutional investors and toughening rules on a holding company structure, which would make it difficult for family members to restructure their groups, analysts said.

Hyundai Motor Group has not implemented any major restructuring as Chung, who turned 79 on Sunday, has shown no signs of handing power to his only son Chung Eui-sun.

“It is reasonable to think that this is the last chance to reorganize the group. But I am not sure whether this will actually happen because it is up to the chairman to decide,” said Ko Tae-bong, an analyst at Hi Investment & Securities.