CleanSpark, Inc.

Strategy, formerly MicroStrategy, is a US software company that turned itself into the largest corporate holder of bitcoin. It has been buying since August 2020, funded mostly by selling shares and bonds.

Metaplanet is a Tokyo-listed Japanese company that keeps its reserves in bitcoin, often called “Asia's Strategy”. Its goal is to own 210,000 BTC, 1% of all bitcoin, by the end of 2027.

A spot bitcoin ETF is a fund traded on a stock exchange that holds real bitcoin. It lets people get bitcoin price exposure through an ordinary brokerage account, without holding keys themselves.