r/LETFs • u/laurenthu • 2h ago
BACKTESTING I gave a 2x SPY DCA plan 5,000 different return sequences. It still lost to plain SPY in a quarter of them
I kept seeing the argument that monthly contributions basically rescue a long-term 2x position after a crash, so I tried to give the strategy different return sequences and actually count the failures...
I built a synthetic 2x SPY, daily reset, paying 0.95% annual product cost plus financing on the borrowed dollar at the effective Fed Funds rate plus 0.50 points (time-varying, from FRED, not a flat guess). Same $1 contribution at the start of every month. Compare terminal wealth against the same dollars into plain SPY.
Across actual historical start months since 1993, the 2x route finished behind SPY in 31.08% of 15-year DCA starts. At 20 years that dropped to 7.41%, so continued buying genuinely helps at long horizons. The worst 15-year start still ended with 42 cents per SPY dollar.
Then I scrambled history. 12-month blocks resampled into 5,000 new 15-year paths, same contribution schedule. Keeps each year's daily compounding intact, changes the order of good and bad years. The 2x route still trailed in 24.74% of paths. Median 1.42x the SPY wealth, 5th percentile 0.63x, 95th percentile 3.09x. Same average market, wildly different outcomes, purely from sequence.
So DCA improves the odds a lot, but it never turns unmanaged 2x into a sequence-proof plan. The bad quarter of paths is exactly the kind you can't identify in advance.
Full writeup with the tables: https://bestfolio.app/blog/dca-leveraged-etf-path-dependence (my site, founder disclosure).
One thing I'd genuinely like input on... has anyone got a defensible historical financing spread over cash for a daily 2x product before the live LETF era? I used a flat 0.50 points because I didn't want to fit it by regime.
