They may look to own more of the company - but at a lower price. A story like this could cause the stock to dip - especially if seen coming from a 5.8% minority owner. A large enough stake that it looks like they are concerned, but small enough that they don't have the direct access to Yahoo! to rectify.
Going further, a dark knight takeover strategy is to quietly pool the shares that multiple companies have -> into one company that then owns a majority stake or has enough votes to exert decisions in their favor.
I'm not saying this is the intent here, but one of the first steps down the path.
This tactic will most certainly get the SEC on you. There is a reason why they (the SEC) force those who own or 'control' 5% or more of a publicly traded company to disclose that ownership or control.
