What type of investments can I invest my cash balance plan in?

As far as investments are concerned, you have the flexibility to invest your funds as you see fit. You can invest in basically anything you want. Most people will do stocks, bonds, mutual funds, CDs etc.

But you can also do real estate, etc. The big issue is that if you do real estate, you need to make sure that you can give our actuary a value at the end of the year. We need to have a fair market value of all assets in the plan as of the end of the year in order to run our calculations.

Here is an article on the topic: https://www.emparion.com/what-are-my-defined-benefit-plan-investment-options/