Up until this past December, I kept $2K in cash and the rest was very aggressive growth. I did this because I consider the HSA to be better than even a Roth IRA as a long term investment option, and keep my pre-tax (mostly 401k) accounts conservative in order to keep my total portfolio somewhat balanced. I jumped 90% out of the stock market in early December, because I thought the P/E ratios were getting absurd, and that made me nervous. Market timing is dangerous, but it looks like a win this time around. I have less in my Roth than my HSA, but the Roth is also the only account I have direct stock trading available, so I mostly buy individual dividend stocks I intend to keep for decades; so it's hard to determine just how aggressive that account actually is.
That said, I intend to return to a very aggressive stance inside my HSA about July, after the bulk of the carnage is past.