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: Shares of electric-vehicle maker Tesla Motors (Nasdaq: TSLA) sank as much as 13% in early Monday trading as the 180-day lock-up agreement from its IPO expires.

So what: Last week, Morgan Stanley estimated that the end of the lock-up period, or the point when insiders can start selling on the open market, could triple the number of Tesla shares available for trading. So when you combine that potential surge in "supply" with the fact that Tesla shares are up significantly since its IPO, it's easy to understand investors' concerns.

Now what: I wouldn't be so quick to pounce on today's plunge. Double-digit declines over imagined insider dumping aren't worth getting worked up about, but when you consider that Tesla lacks any real scale to compete against green-focused giants Ford (NYSE: F) and Nissan, I know I'd be selling at the first opportunity. With skepticism steadily growing on Wall Street about just how fast Tesla will be able to grow, Mr. Market might not be ready to support the flood of new shares.

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

Fool contributor Brian Pacampara owns no position in any of the companies mentioned. Ford Motor is a Motley Fool Stock Advisor selection. Try any of our Foolish newsletter services free for 30 days.

True to its name, The Motley Fool is made up of a motley assortment of writers and analysts, each with a unique perspective; sometimes we agree, sometimes we disagree, but we all believe in the power of learning from each other through our Foolish community. The Fool's disclosure policy always gets a perfect score.