This is not money to put in the stock market.
--The timeline is too short. You will use it all within four years; you will use some of it every six months.
--You need a specific amount at specific times, regardless of what the market is doing.
The market is for money you don't need too soon, where you can afford to ride out the lows, and/or be flexible in the amount you choose to pull out. If the market drops and stays down for a year, you'll still have to sell at a specific time, which may mean locking in a big loss; toward the end, you might not actually have as much as you need, if the market is still down. (Your last 9,000 melted into 6,000, what to do?)
Bonds and CDs are designed for this kind of situation. You give up some ROI in return for the security of a predictable return and having it when you need it.
