SEOUL, March 15 (Reuters) - Shares in South Korea's Samsung C&T fell by 10% on Friday after shareholders defeated a proposal by activist funds to lift dividend payouts, disappointing investors amid a government push to lift the value of Seoul-listed companies.

Samsung C&T is the Samsung conglomerate's de-facto holding company, with Samsung Electronics Chairman Jay Y. Lee the largest shareholder.

At its annual general meeting (AGM), Samsung C&T shareholders voted 77% to 23% to back the board of directors' shareholder return plan, rather than the plan from activist funds, a company spokesperson said, without commenting further.

Huh Jae-hwan, an analyst at Eugene Investment Securities, said the vote was symbolic because it is Samsung.

"It was an event that raised doubts over whether there would be real changes in companies' shareholder returns and worries that it would still take a long time for improvements in governance structure of Korean companies," Huh said.

Still, the 23% vote for the activist proposal was high compared with similar attempts in the past, and given that retail investors don't usually attend the AGMs, analysts said.

After the vote, Samsung C&T shares dropped by as much as 10.1%, retreating from a more than eight-year high hit on Thursday, ending the session with their worst daily performance since May 2015.

Last month, South Korea unveiled a corporate reform plan, dubbed the "Corporate Value-up Programme", in an aim to tackle the so-called "Korea discount".

The discount refers to a tendency for Korean companies to be undervalued compared with global peers due to factors such as low dividend payouts and the dominance of opaque conglomerates known as chaebols.

Earlier this year, a group of Samsung C&T shareholders, led by ANDA Asset Management, City of London Investment Management Company and Whitebox Advisors, submitted a proposal to raise annual dividend payouts to 4,500 won ($3.38) per common share and 4,550 won per preferred share.

That compared with the board's proposal of 2,550 won per common share and 2,600 per preferred share, which is a total of 417.3 billion won worth of dividends, already up 11% from 376.4 billion the previous year.

Shareholders also voted down 82% to 18% the activists' proposal to allocate 500 billion won to a share repurchase programme.

"Investors' hopes were a little excessive, given that the activist funds' demand was rather unreasonable, and Samsung had already announced its own plan for shareholder return," said Kim Soo-hyun, an analyst at DS Investment Securities.

"That said, Samsung may be less motivated than others, because its succession process is already set out and ongoing," Kim said.

South Korea's National Pension Service (NPS), a major stakeholder in Samsung C&T, voted for the board's proposal, saying the activists proposal was "too much", a day after NPS said it supported the government's corporate reform plan. The state pension fund has big stakes in major conglomerates.

On Thursday, South Korea's financial market watchdog met with asset management firms and urged them to vote in ways that boost investor returns and corporate value at AGMs in March.

($1 = 1,329.4200 won) (Reporting by Jihoon Lee; Editing by Ed Davies and Tom Hogue)