I’ll go with the others and say use a simple three fund portfolio.
The general idea is, if you are comparing your performance against an index, why not just buy the index? Most investors fail to beat the S&P 500, so if you buy an S&P 500 fund, you’ll be doing better than most over the long term.
Here’s my personal target portfolio:
US stocks - 70%
International stocks 30%
cash and bonds - 0%
Instead of going for an index like the S&P 500 that targets the top 500 companies, I want to buy all the companies at market weight. So here’s my ideal portfolio with US Vanguard funds:
VTSAX - 70%
VTIAX - 30%
BND - 0%
My actual portfolio is a bit messier because of fund availability, but it’s pretty close to the above. For example, my workplace doesn’t have a cheap total US market fund, so I split between an S&P 500 fund and a small cap fund in an 85/15 split.
I’m considering adding bonds now that yields are more interesting and I’m almost close enough to retirement to start ramping in to them, but for now I only own a handful of short term treasuries as part of my efund. But if I did own bonds as part of my retirement portfolio, I’d either own or approximate BND.