What exactly is the reason for the rapid spike in MSTR's premium? Did the fundamentals of MicroStrategy's 'issuing debt to buy coins' change?

Answer: Yes. This fundamental change is called “premium increase”. Since the middle to end of last year, MicroStrategy has adopted a new way of buying coins, that is, by issuing additional shares of MSTR and selling them to buy more bitcoins. This 'sell shares to buy coins' strategy may seem silly at first glance, and may not only hurt the stock price, but may even threaten MSTR's 'leveraged bitcoin' market positioning.