By Arasu Kannagi Basil

March 11 (Reuters) - Janus Henderson ( JHG ) said on Wednesday its board had determined that Victory Capital's ( VCTR ) proposal to buy the asset manager was not superior to the take-private deal with Nelson Peltz's Trian and General Catalyst.

San Antonio-based Victory last month made public its $8.6 billion offer for Janus, ratcheting up pressure on the company that had agreed to a $7.4 billion buyout by Trian and General Catalyst.

Victory's latest proposal is not actionable because it presents "significant closing risk and uncertain value," Janus said.

Janus noted a variety of factors including significant uncertainty in obtaining the required 75% client consent threshold to close the proposed Victory deal.

"Some of our most important clients told us they would have significant reservations about maintaining their relationships with us if we moved forward with Victory Capital ( VCTR )," Janus CEO Ali Dibadj said in a memo.

Victory Capital ( VCTR ) said in a statement that Janus did not "engage substantively" with its proposal.

"The issues cited by the Special Committee to support its decision could be addressed through substantive engagement, and Victory Capital ( VCTR ) remains fully committed to pursuing this compelling opportunity," it added.

Janus shares closed down 0.6% on Wednesday, while Victory rose about 1.6% in the session. The companies' stocks were last flat after the bell.

Victory's synergy targets also suggest aggressive cost cutting that could lead to the disruption of systems and services, attrition of investment staff, and deterioration in compliance, Janus said.

"We would not expect another party to enter the discussions, as that too would likely need to drive significant cost savings," TD Cowen analyst Bill Katz said.

"Whether VCTR looks to sweeten the offer or alter the funding mix remains to be seen, but given the risks addressed by JHG's special committee, its advisors and the board, it would seem difficult for such a combination to arise."

Trian, which owns 20.7% of Janus stock, has also reiterated it will vote against and solicit opposition to the Victory proposal, Janus said.

Janus also said Victory had not offered to pay the $297 million termination fee if the Trian and General Catalyst deal is called off.

The company reaffirmed its recommendation that shareholders vote to approve the Trian-led deal at the April meeting.

(Reporting by Arasu Kannagi Basil in Bengaluru; Additional reporting by Manya Saini; Editing by Krishna Chandra Eluri and Sriraj Kalluvila)