What to know:

• Long-term bitcoin holders, seen as "smart money," have sold more than 1 million BTC since September.

• In previous cycles when they rein in sales, it tends to mirror a top in the cycle for the bitcoin price.

Long-term holders of bitcoin (BTC) seem to ended their selling spree, a change in strategy that's helped convert the psychological $100,000 resistance price into a support level for the first time.

With one, short-lived exception, the largest cryptocurrency has held above $100,000 since Jan. 17. The past few days have been extremely volatile due to President Donald Trump's inauguration, which saw a spike in volatility.

Long-term holders, or investors who have held bitcoin for over 155 days, have been among the biggest contributors to selling pressure on the market, according to CoinDesk research in December. They are deemed "smart money" because they tend to buy when bitcoin prices are depressed and sell into strength, a pattern that's been observed over the past four months.

In September, this cohort held 14.2 million BTC. It now holds 13.1 million BTC. While the investors held back around the start of the year, sales have picked up again in recent days as the price rose, though at a reduced pace.

The trend to watch out for is when they stop selling. This tends to mark a top in the cycle, which has occurred in 2013, 2017, 2021 and 2024.