Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: After booking a tidy 4% gain yesterday, shares of mobile telephony IP shop InterDigital (Nasdaq: IDCC) are moving even higher this morning, up as much as 10% at one point.

So what: Yesterday, InterDigital's board announced that it's definitely interested in selling the company "in whole or in part."

Now what: That "in part" part is key. Rumor has it, you see, that interested buyers were bidding as low as $1 billion and $2 billion for InterDigital -- numbers that spooked investors hoping to see something more along the lines of the $4.5 billion that a consortium including Microsoft (Nasdaq: MSFT), Research In Motion (Nasdaq: RIMM), Apple (Nasdaq: AAPL), and EMC (NYSE: EMC) paid for Nortel's patent portfolio earlier this year, or the $14 billion that Google (Nasdaq: GOOG) shelled out for Motorola Mobility (NYSE: MMI). This fear sparked a sell-off in InterDigital stock on Monday.

Turns out, however, that the $1 billion bids were actually for just a part of InterDigital -- meaning the whole of the company could still be worth something in the neighborhood of a Nortel (or a Motorola?). And this confirmation, Fools, is why InterDigital is going right back up again.

What price will InterDigital ultimately fetch? Will it find a buyer at all? Add the stock to your Fool Watchlist and find out.

Fool contributor Rich Smith owns shares of Google. The Motley Fool owns shares of Google, Research In Motion, Apple, Microsoft, and EMC. Motley Fool newsletter services have recommended buying shares of InterDigital, Microsoft, Google, and Apple, as well as creating a bull call spread position in Microsoft and Apple. Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.