Starbucks' share price plunge: Is its business maturing?

After holding its quarterly earnings call on Wednesday, Starbucks (SBUX) was hammered: it had fallen 12% to $29.38 in pre-market trading as of 8:30 a.m Thursday. The stock recovered a bit during the day to close Thursday at $30.64 for a $2.66, or 7.99% drop from the prior day's close. I would have expected more upside this morning, but the stock is only up 16 cents in pre-market as of 8 a.m. (and it was negative about a half hour ago).

What explains the plunge? While Motley Fool staffers confess to finding Starbucks "consistently impressive numbers" becoming almost boring, Britain's The Guardian focuses on the company's admission that wait times in the morning for frappucino and other cold drinks are lagging behind customer demand, just as much of Wall Street seems to have done.

Of course, the explanation is not as simple as these factors. When a company consistently reports same-store earnings at the high-end of expectations, this quarter's report at the low end of expectations (4% actual, with prediction being between 3 and 7%), may strongly reinforce what many believe: namely that there could not possibly be more growth potential left in this seemingly ubiquitous enterprise.

For those with that frame of mind, a low result on earnings could be just the clue they need to decide that the fruit is off the vine, and Starbucks is now a mature business.

That will certainly be the situation some day, but it's not a belief I share yet. I'll keep looking at the company with great interest -- especially internationally, which is where, if this stock is to rebound, its future lies.

Michael Canfield is a private investor, a business and media writer, living in Seattle. He doesn't own stock in Starbucks.