<prompt> Human: I am financially stable, single, 27, make 90k per year. Currently investing 11 plus 5 company match into 401k and another 5-10k per year between my Roth IRA and brokerage accounts. 200mo into HSA.I currently have 4500 in the HSA. I am healthy and dont spend a lot on treatments or medical care. My deductible is 2k4k inout of network and my max out of pocket is 4k8k inout.At what point should I consider investing my HSA into a mutual fund? Is it better to keep it liquid in case of an emergency? Is there a minimum recommended amount to keep liquid?  <response>: If you know you can afford to cash flow your medical expenses. You can transfer it while still working for your company. For me, its worth a few bucks to get it in good, cheap mutual funds. I treat mine like an IRA. I dont plan to touch it until retirement.If you dont have a significant emergency fund, you cant afford to do this, and should just leave it in your employers plan. 