[jjeaff]

VOO fees are 0.05% vs 0.09 for spy.

But of course fees are effectively much higher if you are paying transaction fees.

But vfiax (vanguard) or swppx (schwabb) can't be beat (.04 and .03) when it comes to fees. And it is pretty common for brokers to offer free Mutual fund trades or you can get an account directly with those brokers and trade for free.

[astura]

Don't forget iShares too, which are usually traded commission free for many brokers (I know for Fidelity and USAA...). IVV has an expense ratio of 0.04% and they have other really low cost ETFs too.

[jjeaff]

I think there are some additional internal costs with ETFs that cause it to have lower returns over time. At least, I remember seeing some comparison graphs to that effect.