I edited my post, I looked on my actual vanguard account and there is no VITPX or VITSX. They have the trust versions of the stock and bond indexes and some target retirement funds and 2 international funds, which I edited in my post above. Also, what is your rationale for 100% stocks in 401K and not in the IRA?
Okay, go with 100% "Vanguard Institutional Total Stock Market Index Trust" in the 401k then. It's 0.01% better than VITPX anyway...
As far as the rationale for my recommendation goes, the idea here is to first pick an
overall asset allocation, then buy those funds in the account types where they fit best.
For you, the overall asset allocation you said you were considering, and that I agreed was a good choice, is 100% stocks. But within the category of stocks, you still have to decide "which ones?" US vs. non-US, large cap vs. mid cap vs. small cap, "growth" vs. "value," etc. The simplest choice is to say "I'll just buy everything," so your asset allocation should be all world stocks, weighted by market capitalization. You could accomplish that by buying a single fund, such as
this one. Otherwise, you can make decisions such overweighting US stocks compared to the world market cap (which may or may not be a good idea -- see that other thread again -- but which Americans commonly do), "tilting" towards small or value stocks, or all sorts of other complicated things.
But for now, we'll keep it simple: world market-cap weighting. The trouble is, the single fund listed above isn't a choice in all of your accounts (at least not in your 401k). Therefore, you have to do at least a little slice-and-dice to get other funds containing segments of the market to add up to it, in this case, by combining a US total-market index fund (e.g. VTSAX) with a world-except-US total market index fund (e.g. VTIAX) -- we'll assume a 50/50 ratio for now. So, still keeping it as simple as possible, in each account you could buy 50% VTSAX (or similar) and 50% VTIAX (or similar).
Of course, your 401k doesn't have a world-except-US total market index fund either (it only has actively-managed international funds, which have higher expense ratios and performance characteristics that may stray from the index in either direction). There's no good replacement for the VTIAX half! Therefore, in your 401k you'd instead buy 100% VTSAX-equivalent and then in your other accounts you'd buy more than 50% VTIAX to compensate (so that when summed across all accounts, your overall AA is 50/50).
Finally, the other reason it's a good idea to split your asset allocation up unevenly between accounts is that the different accounts have different tax characteristics, and different asset classes have different tax efficiency. Therefore,
putting the least-tax-efficient assets in the most tax-deferred accounts can save you money on taxes. That's why I suggested putting the VTIAX-equivalent in your taxable account first and then "overflowing" to the IRA if necessary: because then you might be able to claim the foreign tax credit. If you put the US stocks in taxable instead you'd lose out on that for no good reason.
Concretely, with the assumed 50/50 AA and the account balances you mentioned, you would have (currently):
| Account Type | US | International | Total |
| 401k | $0 | $0 | $0 |
| Traditional IRA | $67K | $0 | $67K |
| Roth IRA | $23K | $0 | $23K |
| taxable | $77.5K | $167.5K | $245K |
| Total | $167.5K | $167.5K | $335K |
Then after a year maxing your 401k ($18K) and Roth IRA ($5500) but saving nothing in taxable and assuming 0% return (note the
rebalancing occurring in the taxable account):
| Account Type | US | International | Total |
| 401k | $18K | $0 | $18K |
| Traditional IRA | $67K | $0 | $67K |
| Roth IRA | $28.5K | $0 | $28.5K |
| taxable | $65.75K | $179.25K | $245K |
| Total | $179.25K | $179.25K | $358.5K |
All this is just an example and YMMV, of course.
