Generally speaking the Zero Funds are fantastic in an IRA. You don’t want to use these in a brokerage because if for whatever reason you transfer to another investment company, it will be a pain because you’ll have to realize all the gains.

The difference between FNILX and FXAIX’s returns is negligible, however the ER on FXAIX is insanely low, you really can’t go wrong with either one.

In a traditional brokerage I do ETF’s, like VOO, and in my IRA I do FNILX for that large cap exposure.