Although many health savings account (HSA) owners fund their accounts only to pay their current expenses with pre-tax dollars, a growing number of accountholders are beginning to accumulate balances and invest those funds as they do balances in other long-term vehicles like qualified retirement accounts.

According to industry analysts at Devenir, there are now more than 26 million health savings accounts, holding $61.7 billion in assets. HSA investments assets grew to an estimated $13.3 billion at the end of June 2019, which is up 35 percent year-over-year. That figure represents an increase from $4.2 billion only three years before and about $200 million in 2008.

What’s driving this growth? Let’s look at three important factors.