"On Jan. 31, just before Microsoft’s uninvited bid for Yahoo became public, Yahoo closed at $19.18."

Now, after reporting good quarterly results, they are trading at $24.04.

The sky isn't falling.

Update: that puts Yahoo up 23% since Jan 31st. For comparison Google is only up 5% over the same period.

I agree, but keep in mind that it has been only one day. This could keep going for some more time.

That is very true. Hopefully Yahoo's new Open initiative will help them to gain visibility and search market share.

comparing yhoo to goog, is definitely apples to oranges, I would suspect (at least my intuition says) that the higher your stock price, the harder it is to gain percentages. so google being up 5% ($29.5) and yahoo being up 23% ($5.65) doesn't really correlate;

from an investor point of view it's a fair comparison.