Bitcoin mining companies are under heavy pressure from the bear market, and by the end of this year, their collective debt will exceed $4 billion. First, Bitcoin mining company Core Scientific was the hardest hit, owing up to $1.3 billion, and has now filed for bankruptcy protection. Secondly, Marathon Digital mining company is also heavily in debt, owing about $851 million, because most of the convertible notes can be used by creditors in exchange for company shares.