* ISS says Buffett benefit has already been realized
* Shareholder vote to be held on Sept. 12
* Glass Lewis supports plan for Buffett to increase stake (Adds Glass Lewis recommendation)
TORONTO, Aug 30 (Reuters) - Home Capital Group Inc could face a revolt over U.S. billionaire Warren Buffett's plan to increase his stake in the business after proxy advisory firm Institutional Shareholder Services (ISS) recommended shareholders vote against it.
Home Capital and Buffett's Berkshire Hathaway Inc investment vehicle agreed in June to a deal worth up to C$400 million ($318 million) for an initial stake of 20 percent in the business. The position could increase to 38 percent if Home Capital shareholders give approval in a vote on Sept. 12.
Under the terms of the deal, Berkshire Hathaway can purchase the additional shares at a price of C$10.30 per share. Shares in Home Capital rose 1.6 percent to C$13.45 on Wednesday.
Home Capital benefited from Buffett's initial investment as well as from a C$2 billion credit facility. The deal helped rebuild confidence in the financial strength of the company after depositors withdrew funds from its high-interest savings and Guaranteed Investment Certificate accounts.
Home Capital's executives had emphasized the importance of having an investor of Buffett's credibility backing the company.
However, ISS said much of the benefit is already in place after the initial transaction and questioned the benefits for Home Capital's shareholders of Buffet increasing his stake.
"The proposed Berkshire second tranche appears to offer nominal additional reputation and strategic benefits to those already established under the Berkshire first tranche, while dilution cost of the discounted second tranche is substantial," ISS said in a statement.
Proxy adviser firm Glass Lewis recommended that Home Capital shareholders vote in favour of the deal. Glass Lewis said it believes decisions regarding a company's business operations, such as financings, are best left to the judgment of the board.
"We believe the additional capital provided by the private placement will provide the company with sufficient flexibility to pursue its strategy, which we believe is in the best interests of shareholders," Glass Lewis said in a statement.
Investors withdrew more than 90 percent of funds from Home Capital's high interest savings accounts earlier this year.
The withdrawals accelerated after April 19, when Canada's biggest securities regulator, the Ontario Securities Commission (OSC), accused Home Capital of making misleading statements to investors about its mortgage underwriting business.
Home Capital reached a settlement with the OSC in June and accepted responsibility for misleading investors. ($1 = 1.2593 Canadian dollars) (Editing by Jeffrey Benkoe and Chris Reese)