Strategy Inc. — the company once hailed for wrapping crypto exposure into a public stock — is scrambling to calm markets after its shares plunged more than 60% from recent highs, amid a sweeping digital-currency rout. On Monday, Strategy said it had created a $1.4 billion reserve to fund dividend and interest payments, hoping to calm fears that it may be forced to sell Bitcoin if prices fall further. The most popular exchange-traded funds tracking Strategy’s volatile stock — MSTX and MSTU, which offer double the daily return — have both dropped more than 80% this year.