According to Bernstein Research analyst, Toni Sacconaghi, roughly one-fourth of all iPhones in the U.S. have been unlocked.

Approximately 1.45 million iPhones were unaccounted for at the end of last year, although it's believed that AT&T has some 480,000 units in stock; this leaves almost a million out and about, working on other networks. Sacconaghi claims that the unexpectedly high number will put pressure on AT&T to change its business model.

Both AT&T and Apple have declined to comment on the findings, although Apple executives admitted last week that the number of unlocked phones was "significant."

If the trend continues, Apple might miss its revenue and profit goals, but if Apple cracks down on unlocked phones it might end up hurting its sales goals, as well, so it's a lose-lose scenario for Apple in any case.

More here.