Sure, if you want to print a 1000 page supplement and staple it to your taxes.

More seriously, I would still worry about order execution and transaction costs. You are likely to end up on the wrong side of the bid/ask spread when playing against the big boys.

If you're actually serious about this, you might as well start your own ETF. Or just buy this one I found after a quick Google: https://www.proshares.com/our-etfs/strategic/spxt Buying multiple sector-specific ETFs is another approach. I'm told that utilities are good to hold during a downturn.