MicroStrategy (NASDAQ:MSTR), the U.S. software firm that holds almost 130K bitcoin (BTC-USD) on its balance sheet, said it hasn't received a margin call against a bitcoin-backed loan and can withstand more volatility, Reuters reported Wednesday, even as the world's largest cryptocurrency drops toward the $20K mark. In March, the firm took out a $205M loan from Silvergate Capital (NYSE:SI), using some 19,466 bitcoins to secure the loan. Bitcoin (BTC-USD) dropping below $21K would trigger a "margin call," or demand for extra capital to back the loan, MicroStrategy (MSTR) President Phong Le had said in May. On Tuesday, bitcoin (BTC-USD) fell to as low as $20.95K and is down 6.3% over the past 24 hours to $20.6K at 7:17 AM ET. MicroStrategy (MSTR) stock is falling 3.1% in premarket Wednesday trading. The stock has dropped 24% in the past week and 71% since the beginning of the year. Bitcoin (BTC-USD), meanwhile, has fallen 57% during