This is the bucket most people don't know what to do with. You don't necessarily need the money tomorrow but you do need it relatively soon - like for your dream home in the burbs in three years, or an engagement ring, or a new business you're starting.
The stock market could drop 30% right before you need it and that would be a *devastating* time to find out your down payment is no longer there lol.
The best CD rates right now range from 4% to 4.50% depending on who you go to. A two or three year CD locking in a guaranteed rate is genuinely not a bad option for this bucket. Short term bond funds are also worth looking at.
The point is - not fully in cash earning nothing extra, and not fully in the market where it can drop right when you need it.