It's been a slow week in the market as traders, executives, and nearly everyone else seems to be taking time off. But the 10% team has been hard at work scouring the market for the week's biggest stock moves. What did this Fool learn this week?

Pay attention to your IPOs
This week started off with a bang when Tesla Motors (Nasdaq: TSLA) dropped 13% as its 180-day lock-up period ended and insiders cashed out. And this isn't a one-off phenomenon. This year, A123 Systems (Nasdaq: AONE) fell a slightly less dramatic 6% on the day its 180-day lock-up period ended.

If you're a long-term investor, this shouldn't change your investment thesis about a company, but it is something to consider. If you have a shorter time horizon or if you are looking to buy or sell around the time the lock-up ends, you need to pay attention to your IPO details.

Sometimes the FDA confuses everyone
MannKind (Nasdaq: MNKD) jumped and then fell back down Tuesday when the FDA said it would delay its decision on Afrezza for about four weeks. Is this good news or not? Consensus was that no one really knows. Bulls had reason to cheer early, but bears saw it as a sign that the FDA doesn't really care about Afrezza.

Betting on an FDA decision isn't for the light of heart, but Afrezza could be a game changer, so any news makes investors' hearts jump. I bet we'll have another pop/plunge when the FDA speaks again at the end of January.

My biggest lesson for 2010
This year, some stocks have risen more than I could have imagined, and this Fool has left money on the table on some rocket stocks. Both Las Vegas Sands and Apple started 2010 in my portfolio, and I sold both (for a nice profit) far too early. What did I learn? Momentum is a powerful thing in the market, and even if you think a stock is becoming overvalued, it pays to hang on until the rocket fizzles out. I don't know how exactly to tell when that will happen, but hopefully I will learn that lesson in 2011.

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