Bitcoin rebounded over the $44,000 level on Thursday after the cryptocurrency valuations plummeted a day earlier. The global cryptocurrency market cap rose nearly 1% to $1.66 trillion at the time of publishing. Filings by Grayscale and VanEck once again ignited hopes for the approval of a Spot ETF by the U.S. Securities and Exchange Commission. The Grayscale Bitcoin Trust (OTC:GBTC) filed a Form 8-A registration with the U.S. regulator on Thursday. It was noted by Walter Bloomberg that such filings indicated an advancement of applications. The Crypto Fear & Greed Index, a measure of emotions a…