The surge in the yen blamed on retweets

  • Algorithmic platforms are being partly blamed for the moves, according to traders who declined to be identified because they aren't authorized to speak publicly.
  • Keyword flagging in platforms picked up earlier stories reposted at the opening of trade in Asia, the unidentified traders said. Combined with thin liquidity, that was causing excessive volatility before the BOJ decision.

via Bloomberg

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Alternatively:

  • A fund sold
  • Sell order was placed on 103 big figure instead of 105

As I said earlier, take your pick