I'm not so sure. Here's my reasoning, but I'm just using logic, I'm really not super in-tune to this stuff.
If the company knew thought its stock was 10x overvalued (Yahoo's stock did drop 90% a year or so later) then they really only sold it for $570 million. That is, if Yahoo knew its stock would be worth 1/10 of its current value in a year, buying a company with $5.7B in stock will add value to Yahoo so long as The acquired company ends up being worth >$570M.
That being said, if they knew their stock was overvalued, it would be best to issue additonal shares, as $1 is worth $1 regardless. Similiar to how undervalued companies should buy back their stock.