Bitcoin has fallen back below its 50-week moving average, erasing the signal that prompted several analysts to call for a new bull market in September. The last time the signal failed, the price continued to fall below $16,000. On Thursday, bitcoin was trading below $73,400, CoinDesk reports. That's a bit below its 50-week moving average of $75,153. Technical analysts see it as a failed breakout, a sign that sellers have taken over again...