HYSA would be my first choice (4% APY). Highly liquid and hassle free, and literally the purpose of it is for what you are describing. Second would be SPAXX/VUSXX (>5%) which is where I also keep my emergency fund. Though these take like an extra day to cash out compared to HYSA, at least for my bank. I wouldn’t keep in index funds as you described there is a risk to it.
HYSA would be my first choice (4% APY). Highly liquid and hassle free, and literally the purpose of it is for what you are describing. Second would be SPAXX/VUSXX (>5%) which is where I also keep my emergency fund. Though these take like an extra day to cash out compared to HYSA, at least for my bank. I wouldn’t keep in index funds as you described there is a risk to it.