<prompt> Human: I know this subs focus tends to be budget, tackle debt, max tax exempt options followed by low management fee mutual funds.Well as a 29yr old with virtually 0 debt besides a mortgage 3.6, I hammer vanguard funds with my excess cash.Is investment diversity enough with mutual funds?This sub has a boner for Vangaurd, as do I. But if 100 of your savings outside 401KIRA is with vanguard, are you at any considerable risk? Should it be more like 90 vanguard with 10 elsewhere? Maybe 70 Vanguard, 20 land purchases, 10 bank CDs. Im mostly invested into Vanguards Total Stock, Total International Stock, and Healthcare funds.TLDR: Should I really be all in with Vanguard?  <response>: Youre mixing two different things; asset allocation and where those assets are.If you ideal mix is 70 Stocks, 20 Real Estate, and 10 Cash, then Vanguard is definitely appropriate for the stock portion. Is Vanguard the appropriate place for Cash? Probably not.You can absolutely be diversified enough in a stock or bond portfolio in a single mutual fund. Something like a Target Date Retirement fund is a perfect one fund option.Only you andor your advisor can determine what asset allocation you are comfortable with. 