"selling out" doesn't mean anything without an actual quantity number. It doesn't even mean apple underestimated demand, because they could have intentionally understocked to get the "iPhone SE sells out in minutes" headlines.
The best clue that the small phone market is actually a small market is to look to android: the smaller phones don't sell particularly well, especially in the premium tiers. The only company really making a go at the small phones is sony, and they're basically failing.
The best clue that the small phone market is actually a small market is to look to android: the smaller phones don't sell particularly well, especially in the premium tiers. The only company really making a go at the small phones is sony, and they're basically failing.