Investing RMD

I am 73 in 2024 so have to start my RMD.

 

I really don't need the cash right now so was thinking of investing it in the same funds I use for my 401.  Trying to plan a post 401k strategy.

 

So lets say my RMD is $25,000.  I know that will get taxed ad ordinary income.

 

If I put that $25,000 into an investment fund, how will that get taxed if I withdraw any cash?  Or are only dividends and/or interest on that fund taxable.

 

Thanks