March 20 (Reuters) - Trian Fund Management on Friday said it has serious concerns about Victory Capital's ( VCTR ) sweetened offer for Janus Henderson ( JHG ) that rivals its own take-private deal with the asset manager.

Janus had previously rejected an $8.6 billion cash-and-stock offer from Victory, saying the bid carried closing risk and was not superior to the existing $7.4 billion all-cash deal with Trian and venture capital firm General Catalyst.

But Victory revised its offer earlier in the week to include a higher cash component.

Janus Henderson ( JHG ) declined to comment. Victory Capital ( VCTR ) did not immediately respond to Reuters requests for comment.

Trian is Janus' largest shareholder with a 20.7% stake.