Let’s say you plan to buy a house in 12-18 months. You have the money for a down payment, but it’s in the market right now (combo of ETFs and individual stocks). 

Do you:
(1) Keep the money in the market but in a more conservative portfolio 
(2) Put the money in a savings account and sit on it
(3) Something else

It's a numbers thing like people have said but unless your looking at like 5-10k in yield it's probably not worth it and you're better off getting some small yield in bonds. Also depends how hard your timeline is. NFA just the mindset I went through when I had to do the same