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: This has to be getting tiresome. After big declines in June, July, and August, shares of Clearwire (Nasdaq: CLWR) closed down another 11%. This time, worries over the cost to bring Apple's (Nasdaq: AAPL) iPhone to its parent carrier, Sprint Nextel (NYSE: S), appears to have caused the selloff.

So what: Like a climber stuck in an avalanche, investors sold on fears that fresh commitments to Apple could leave Sprint unable to provide additional financing to cash-strapped Clearwire.

Now what: It's a fair concern. The WiMAX specialist's debt is virtually equal to equity and 50% of total capital as of this writing, a structural weakness that begs for help that Sprint isn't in a position to provide. Do you agree? Would you buy shares of Clearwire at current prices? Please weigh in using the comments box below.

Interested in more info on Clearwire? Add it to your watchlist.