Bitcoin (BTC-USD) slips 2.8% to $47.1K in the past 24 hours, retreating from $50K resistance level. Some chart patterns show the the cryptocurrency's rally since mid-July is at risk. John Bollinger, inventor of Bollinger bands, said it may be time to "take some profits or hedge a bit," in a tweet on Wednesday. "Aggressive traders can think about putting out some shorts." Bloomberg's Akshay Chinchalkar notes that narrowing Bollinger bands indicate that the Bitcoin rally is fading and Bitcoin faces a $50K-$51K zone of resistance, with a $46.7K a key threshold to watch. Katie Stockton at Fairlead Strategies says DeMark market-timing indicators point to about two weeks of "sideways-to-lower" prices, Bloomberg reports. CoinDesk's Omkar Godbole says the Bitcoin turbulence comes ahead of monthly options expiration. A total of 42.5K option contract worth ~$2B are set to expire on Friday, according to Skew data. "Data since January show bitcoin tends to move toward the