The entirety of the article is summed up with this statement hidden inside.
> Mr. Amador attributed the underperformance to a normal variability in returns. The fund’s programming beat the market when tested against historical data, he said, and he expects the same in real life as time passes.
Backfitting in all its forms is known to give false confidence and usually fails. It may work for a moment, but then other traders exploit whatever the backfitting had noticed causing the backfit to no longer work.
> Mr. Amador attributed the underperformance to a normal variability in returns. The fund’s programming beat the market when tested against historical data, he said, and he expects the same in real life as time passes.
Backfitting in all its forms is known to give false confidence and usually fails. It may work for a moment, but then other traders exploit whatever the backfitting had noticed causing the backfit to no longer work.