Legg Mason, a 4.4% institutional shareholder, said it was likely to vote to retain Yahoo!'s existing board of directors at the meeting on August 1.
Icahn, frustrated that the Yahoo! board continues to oppose doing a deal with Microsoft, last week put forward his own slate of nine board candidates with the aim of ousting Yang and his fellow directors.
While Legg Mason's chief investment officer Bill Miller was supportive of Yang, he would like to see Microsoft make another offer. However, it has not returned with an offer since Yahoo! rejected Microsoft's joint approach with Icahn to buy Yahoo!'s search business on July 15.
Another shareholder was reported to have put forward a proposal that would re-elect five existing Yahoo! directors together with four of Icahn's candidates.
Eric Jackson is the founder of the activist hedge fund Ironfire Capital and leader of a Yahoo! shareholder group called Yahoo Plan B, which comprises 150 individuals accounting for just 0.23% of the company.
Many shareholders are likely to follow the advice suggested by specialist proxy advisory firms, such as ISS Governance Services.
The WSJ reported that Yang and his colleagues gave no indication to ISS they would settle for offering Icahn four board seats as a compromise.
Yahoo!'s share price closed on Friday at $22.45, which was down 4.8% over the week.