Institutional Shareholder Services (ISS) told shareholders to support Michael Dell and Silver Lake Management’s $13.65-per-share buyout proposal in a note sent out this morning. Glass Lewis and Egan-Jones Proxy Services, two other prominent advisory firms, also endorsed the bid in separate statements issued a few hours later.

“After evaluating the risk of accepting the offer…ISS recommends clients vote FOR this transaction, which offers a 25.5% premium to the unaffected share price, provides certainty of value, and transfers the risk of the deteriorating PC business and the company’s on-going business transformation to the buyout group.”

ISS’s decision came as a surprise for the special committee of Dell directors charged with supervising the company’s sale. Anonymous sources told Bloomberg that the advisory firm was against Michael Dell’s offer as recently as last week.

The blessings of ISS, Glass Lewis and Egan-Jones will go a long way in swaying investors to vote in favor of the $24.4 billion proposal later this month. The bid is currently under fire by hedge fund giant Carl Icahn and Southwest Asset Management, two prominent stakeholders that argue Dell is worth more than $13.65 a share. Icahn and Southwest propose a $15.6 billion self tender that would keep the company public but allow investors to cash their shares for $14 apiece. According to a report from Glass Lewis, Icahn, Southeastern and the other stakeholders who oppose Michael Dell’s offer own over 20 percent of Dell’s stock.

Up until today, Icahn had a definitive lead in the race for the company’s future. The activist investor secured a $5.2 billion loan from Jeffries earlier this month, and  slammed the special committee for promoting Michael Dell’s proposal and avoiding direct negotiations with his delegates.