Back in 2011, BlackBerry (NASDAQ:BBRY) took a huge inventory writedown related to a glut of unsold PlayBooks. After everything was said and done, the company was looking at a pre-tax noncash charge of roughly $485 million that it had to eat. The company got ahead of itself and built way too many PlayBook tablets that it couldn't' sell.

Could the same fate befall its growing inventory of BlackBerry 10 devices?

Deja vu
One reason why some Street analysts had become so bullish on BlackBerry heading into the earnings release was that supply checks showed BlackBerry's build plans steadily increasing. This was the first full quarter of BlackBerry 10 availibility, and rolling out the Z10 and Q10 into the company's global distribution channel was also expected to give a boost since sales are reported based on channel sell-in.

Well, sell-through is ultimately what matters as the best indication of consumer interest. There had been reports of high return rates, which BlackBerry staunchly denied.

Regardless, what investors now know is that even after filling the channel with BlackBerry 10 units, the company only shipped 2.7 million units. As a result, BlackBerry may have a glut of unsold inventory... again.

Bbry Inven Labels

Source: Morningstar. Fiscal quarters shown.

The company's inventory carrying value on its balance sheet has just skyrocketed by an incredible 47% sequentially to $887 million. That figure has climbed for the past two quarters, and is now slightly above where it stood immediately after the PlayBook writedown.

BlackBerry has improved its supply chain efficiencies, which helped reduce its inventory carrying balance down to $457 million a couple quarters ago. The company now has nearly twice as much sitting on the books.

Launch quarters should also be marked with the highest sales due to pent-up demand, yet BlackBerry still fell short. Sell-through to end consumers is what matters most now, and since they don't seem to be buying the Z10 or Q10 in droves, BlackBerry may be facing another inventory writedown in the near future.

Fool contributor Evan Niu, CFA, has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.