Publicly traded US crypto mining companies doubled their bitcoin (BTC) holdings last year, taking the total to 92,473 worth $8.6 billion at the end of December, while the price of the largest cryptocurrency rose 120%, according to data from TheMiningMag.

The largest amount, almost half of the total, is owned by MARA Holdings (MARA) with 44,893 BTC. MARA has the second largest inventory among publicly traded companies, surpassed only by MicroStrategy’s (MSTR) 450,000 BTC.

The strategy of investing in bitcoin and holding it for the long term, known as HODL after a typo made more than a decade ago, has grown in popularity in the past 12 months.

Three other miners have more than 10,000 BTC: Riot Platforms (RIOT) with 17,722 BTC, Hut 8 (HUT) with 10,171 BTC, and CleanSpark (CLSK) with 10,097 BTC, according to Bitcoin Treasuries.

Not all miners subscribe to the HODL playbook. IREN (IREN), TeraWulf (WULF), and Core Scientific (CORZ) all have very little or no bitcoin. Due to the competitive nature of the business, these companies have shifted into the artificial intelligence (AI) and high performance computing (HPC) industries.

Stock prices have not matched bitcoin’s trajectory. In general, miners underperformed bitcoin and other crypto-related stocks, such as MicroStrategy. Outstanding performers Core Scientific and Terawulf both achieved over 300% returns with their new AI focus.

This year the miners that HODL bitcoin have benefited greatly though, with RIOT, HUT and CLSK all outperforming bitcoin. Only Bitdeer (BTDR) has generated negative returns after seeing a strong performance in 2024.