JUST IN: MARA pledges 18,750 BTC to back $600 MILLION in new loans. MARA Holdings, one of the largest Bitcoin miners, secured $300 MILLION each from Coinbase Credit and Two Prime, against Bitcoin worth $1.2 BILLION at closing. The pledged coins make up 53% of MARA's total holdings and can be liquidated if BTC falls below required levels, per a quarterly filing.(Coin Bureau)