I prefer ETFs, so I would suggest "Schwab Broad US Market" (symbol: SCHB ) since it has almost 2,500 U.S. stocks, instead of just 500. You can search for "SCHB" and click on the link to a Schwab website to get details from them.
Sticking with Schwab ETFs, I would add international as well. Maybe 1/5th of your stock market exposure?
Schwab International Equity ETF (SCHF).
Note both funds are very efficient: they only consume 0.03% and 0.06% of your investment each year (silently), also known as the "expense ratio". If you only pay attention to one thing, look for the lowest expense ratio.