Along with the lower commissions and better fills with the larger SPX & NDX, vs. SPY & QQQ, the tax advantages, as guru alludes to, can be significant. Non-equity options (which includes equity index and future options) are subject to the 60/40 rule....where 60% of your net trading profits are subject to 20% long-term capital gains.
Let's say you net $1M in trading profits for the year.
If you were trading only SPY or QQQ equity and options your income tax bracket is 37% and you'd pay $370k in Federal taxes.
If you were trading only SPX (or ES) options (and maybe delta hedged occasionally with ES futures) your Federal tax bill subject to the 60/40 rule is as follows:
- You only pay 20% long-term capital gains on 60% or $600k of the $1M = $120k
- You pay regular Fed taxes, say 35%, on the remaining 40% or $400k = $140k
- Total Federal taxes: $120k + $140k = $260k (or 26%)
In total, if you net $1M in trading profits, you save $110k in Federal taxes trading SPX, ES, or NDX vs trading SPY or QQQ. $110k gets you an entry level 911 Porsche Carrera.