4. MARA

Bitcoin mining company MARA (formerly Marathon Digital), unsurprisingly, is also a large holder of Bitcoin, with around 38,689 BTC—more than $2.9 billion worth—in its corporate treasury at the time of writing.

The company, which originally aimed to build "the largest Bitcoin mining operation in North America at one of the lowest energy costs," originated as a patent holding firm (and was often referred to as a patent troll) before its pivot into crypto mining.