Shareholders of Yahoo! (YHOO) stock are likely to lose a high percentage of their investment later today when the markets open. YHOO stock closed Friday at $28.67/share.

The stock had risen $9.49 over the past month due to Microsoft’s (MSFT) bid to buy the company for $30+ a share. Reports indicate that MSFT offered $33/share Saturday to Yahoo! CEO Jerry Yang. Yang turned down the offer and countered with $37 bucks a share. Microsoft wisely walked away from the table, ending negotiations in the process.

So Yahoo! shareholders and experts alike agree that the stock is set to get hammered today. It could fall up to 33% according to some pundits. Some predict it will drop all the way back to $19.18/share.

I believe it will lose a couple bucks a share tomorrow but not lose all of its gains since Microsoft approached Yang. A lot of investors will panic and dump the stock tomorrow, but many wise investors will snap up the discounted shares thinking that the MSFT-YHOO dance is not over just yet.

Microsoft is trying to power up to compete against internet giant Google (GOOG)