I always wondered what tools the Fed had left after interest rates were dropped to 0. Negative interest rates are a thing, but I don't think it's a continuous

I always wondered what tools the Fed had left after interest rates were dropped to 0. Negative interest rates are a thing, but I don't think it's a continuous transition in the practicalities of going negative. It seems like the Fed was caught a bit off-guard with the latest inflation, though.