The UK Pound Sterling plunged to a fresh 31-year low on Friday, unsettling stock markets in early Asian trading before recouping some of the losses.  It's not entirely clear why the "flash crash" happened.

As one trader in Tokyo noted, "This was even a bigger move than what we saw after the Brexit vote."  But unlike with the Brexit, there was no negative news linked to plunge:  "There were almost no offers, no bids when this happened," he said.

The Pound was off nine percent from late US levels, trading at US$1.1491.  That's lower than key support levels, and it triggered a wave of selling. An early trade even lower than that was later canceled.  By the afternoon, it was around US$1.2455, still down about 1.3 percent.

Sean Callow of Westpac in Sydney said, "The whole thing's been on a precipice since Sunday, since Theresa May (pointed to) March Brexit negotiations, but the selling has been very substantial so you can only think its been part of that general punishment of the pound for Brexit."  Mr. Callow added, "I think we've underestimated how many people had money positions for a very wishy-washy Brexit or even none. May's comments have really just started the cleanout and we just haven't seen any sign of bouncing."

Another POV blames French President Francois Hollande, who told British reporters that the European Union must take tough stance in negotiating Britain's exit.  Others said it might have just been an accidental "fat finger" mistake that took on a life of its own.