Vanguard's Federal Money Market fund pays 0.02% per year, which would amount to about $1.20 on $6,000. Why are you focused on the cash returns, instead of being invested in equities?
The 1 year performance of the S&P 500 was +18%, or 900x higher than the above money market fund. That return is higher than average, but not rare. Are you using IBKR for investing, or some other purpose?
Why not buy a total stock market ETF (VTI, ITOT, SCHB) or S&P 500 ETF (SPY, VOO, IVV) and leave it to grow?
Mutual funds pool investor's money to buy stocks. With $12,000 it would be difficult to buy 500 different stocks - even harder to buy the 3700 stocks in ITOT or VTI. But the fund or ETF does that for you, and you can then just buy shares of the fund or ETF.