<prompt> Human: Im pretty new to personal finance and I have a hypothetical question. Say another person and I have 500k each to invest, would we get a bigger return pooling both our money into one account with any interest or dividends reinvested for 10 years or would it be totally neglible? This is not accounting for debt, 401ks, iras or personal debt. Assume that both of us are 100 trustworthy. Sorry if this is a dumb question or not specific enough, it was just a curiosity maybe someone can elaborate on.  <response>: From a guy a that works in finance - no this doesnt make sense. We typically quote growth as a percentage. So 5 of growth 1 million but split two ways will be exactly the same as 5 of growth on 500k split one way. Work out the math for yourself, it adds up.Also practically speaking, joint investment accounts are not a good idea unless youre married. It can be messy trying to split up assets. Plus the account will be joint, meaning both parties have equal access. That means your partner can clean out the whole amount if he feels like it and theres nothing you can do about it. Way too much trust to put in another person Im not married to. 