Suppose candidate X raises, through whatever legal means, a million dollars for their campaign. What, if any, ordinarily legal things does national law prevent them from spending this money on?
In particular, would a candidate be able to spend this money on stocks or other financial instruments (presumably, taking on some risk in order to hopefully accumulate more cash before election day)?
Notes: It may be legal, but inadvisable to spend money on certain items - this is fine, my question is primarily concerned with legality. State law may vary, so let's limit this to national rules. Some assumptions may be required to answer this well - feel free to ask in comments or state them in your answer.