Be careful to not lose the forest for the trees. It really doesn’t matter which small cap ETF you use. Just pick one.

The forest is to avoid the large caps. Which small cap you chose won’t be huge as they are extremely correlated. You return will be very different to SPY though.

I like IJS as from longer studies pre-1980 back to 1950 with the Compustat database adding a low price to sales requirement gave an improvement particularly with small caps, though the effect was not there the last 25 years with IJR (without the value related filters) having the same performance. I’ll take the longer data range to make my decision, with no discernable disadvantage with IJS.

If you look over 20+ year averages the performance of all VBR, IJS and IJR are practically the same, don’t worry about it between them if you want to match the S&P600 and just pick one as long as you don’t see high fees. 0.18 for IJS, 0.07 for VBR. However though Vanguard call it small cap, VBR is not a true small cap and closer to a mid cap (whilst IJR is exactly the S&P600) (see etfdb.com - ETF comparison under section 'Market Breakdown') which accounts for VBR's extremely low expense ratio. In the larger picture, all three ETFs have very low fees, the small caps very slightly outperformed mid caps very long-term (though they are amazingly similar) so I would deem it a wash as to which ETF to select and not worry about it.

For the case of AVUV take care though - it run only since late 2019 and AVUV is really interesting as it is an mechanical investing (MI) strategy that filters for low valuation and higher margins. As it did well over just 4 years it on the radar of increasly more people - but that is what happens with all *recently* strong funds and any MI strategy can do well for merely 4 years. The marketing effort pumps up also so we tend to observe the recent well performing as promotion bias. Don’t extrapolate the recent outperformance. There is nowhere near enough data to draw anything from it.

- Manlobbi