Starboard Value's effort to overthrow Yahoo's entire board will be one of the biggest proxy fights in years, and likely one of the most expensive.
While discontent is high among Yahoo stockholders, proxy fights against companies Yahoo's size are rare, and successfully replacing a full board is even rarer. Winning a proxy fight isn't free — companies can spend millions on lawyers, solicitation firms and other costs like mailings to shareholders.
On average, companies spend a few million on a single proxy fight, but Yahoo will likely pay more to avoid a wholesale management change. The costs tend to go up with a company's market cap at the time of the campaign, according to an earlier analysis of FactSet data. Here's how the data look today, categorized by the winner of each proxy fight: