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 South American online auction operator MercadoLibre (MELI -0.45%) plunged 10% today after its quarterly results missed Wall Street expectations.

So what: MercadoLibre's third quarter didn't miss estimates by much -- EPS of $0.59 on revenue of $97.3 million versus the consensus of $0.60 and $98.1 million -- but Wall Street is obviously taking the results as a sign of slowing growth going forward. Operating margins for the quarter even fell to 34.7% from 36.7% in the year-ago period, reinforcing concerns over rising costs and intensifying competition in the space.

Now what: I'd look into this pullback as yet another long-term buying opportunity. "[T]oday we are in a much better position to continue to innovate for our customers while we remain focused on building the most complete e-commerce ecosystem in the region, which we believe is still only a fraction of what it will become," CEO Marcos Galperin reassured investors. Although it's clearly going through a rough patch right now, MercadoLibre's leadership position, wide competitive moat (thanks to strong network effects), and rock-solid balance sheet still make it a particularly intriguing play on Latin American growth.

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