Disney’s largest shareholder, index fund supervisor Vanguard, plans to help administration over Nelson Peltz’s Trian Companions in Wednesday’s board vote, Bloomberg News reported Tuesday, citing unnamed folks accustomed to the matter.

Institutional shareholders have till Wednesday to vary their vote. Vanguard owns 7.8% of Disney shares. BlackRock, Disney’s second-largest shareholder with 4.2% of shares, can also be supporting the incumbent board and CEO Bob Iger, The Wall Street Journal reported Monday.

The reporting on how Disney’s largest shareholders are supposedly voting prompted harsh criticism from onetime activist investor Invoice Ackman on Tuesday night.

“Solely the corporate and its advisors have entry to how shareholders have voted earlier than the day of the annual assembly,” Ackman wrote on social media platform X. “The explanation why the progress of an election for administrators should be stored confidential till the outcomes are remaining is that leaking the outcomes can have an effect on the last word final result.”

Disney shareholders ought to help Peltz’s efforts, Ackman wrote, each as a result of he could be “significantly additive” to Disney and since the media leaks, which Ackman alleged got here from Disney or its advisors, raised the query of why administration was “preventing so onerous to maintain him off.”

It might be a significant blow to Peltz’s ambitions to join Disney’s board if each BlackRock and Vanguard transfer to again the media firm’s candidates. That would go away solely State Avenue and Geode Capital Administration, the corporate’s third- and fourth-largest shareholders respectively, as unknowns.

Via an arrangement with former Marvel Chairman Ike Perlmutter, Trian controls 1.8% of Disney shares, making it the fifth largest shareholder. Retail buyers have till 11:59 p.m. ET Tuesday to submit their vote by cellphone or on-line.

Trian has received help from different, smaller shareholders, together with Neuberger Berman and CalPERS. For its half, Disney has known as in among the most outstanding names within the company and media world, together with JPMorgan Chase CEO Jamie Dimon and Star Wars creator George Lucas.

Disney’s shareholder assembly begins Wednesday at 1 p.m. ET.

Vanguard declined to remark to CNBC.

Read the full Bloomberg report here.