Hudson’s Bay Co. disparaged a shareholder advisory firm’s report that came out against Chairman Richard Baker’s plan to take the retailer private, calling the study “flawed” and reiterating a call to support the deal.

Institutional Shareholder Services Inc. on Friday urged investors to vote against Baker and his partners’ plans to take the owner of Saks Fifth Avenue private for $1.9 billion. In a statement Monday, HBC’s special committee defended its decision to reject a higher competing offer from one of Hudson’s Bay’s biggest shareholder.

The Baker offer “is the only offer available to minority shareholders and provides immediate and certain value at a significant market premium,” said David Leith, the board’s special committee chairman. “ISS acknowledges there is meaningful downside risk if shareholders do not approve this transaction.”

Baker and his partners, who collectively own a 57 per  stake in Hudson’s Bay, reached an agreement to buy the Toronto-based retailer in October for $10.30 a share. The takeover was unanimously supported by the company’s board and is subject to a vote on Dec. 17 that requires the support of most of the minority holders.

The vote pits Baker against private-equity firm Catalyst Capital Group Inc., which owns a 17.5 per cent stake and put forth a rival $11-a-share proposal. The special committee rejected it as “not reasonably capable of being consummated” because Baker and his allies don’t intend to sell their stake, which would in effect kill the offer.

In its report, ISS said Hudson’s Bay offered no clear reason why shareholders should accept the deal when Catalyst offered a higher price. Hudson’s Bay disputed ISS’ rationale, saying an offer is only superior if it can reasonably be completed.

“To terminate the existing agreement otherwise would leave shareholders without the ability to vote on the transaction contemplated by the existing agreement, and with no prospect of having their shares acquired in another transaction,” the committee said.