SIZE vs XMMO

SIZEAiShares MSCI USA Size Factor ETF

XMMOCInvesco S&P MidCap Momentum ETF

In short

SIZE The size factor without leaving the large-cap pool: SIZE holds roughly 500 US stocks and leans toward the smaller names in that universe, spreading weight away from the mega-cap giants. An iShares factor original from 2013.

XMMO Momentum, aimed at the middle of the market. Since 2005 XMMO has screened the S&P MidCap 400 for the strongest price trends and keeps roughly 80 of them, refreshing the list twice a year. A concentrated bet on what's already working.

Stated mandate

SIZE The fund seeks to track an index of U.S. stocks that have smaller market capitalizations relative to their peers.

XMMO The Fund is based on the S&P Midcap 400 Momentum Index.

Why people hold it

• SIZE Charges 0.15%, roughly half the typical fee among US factor ETFs.
• Tracks the MSCI USA Low Size Index tightly, one of the closer index implementations in its peer group.
• Roughly 500 holdings, so no single name dominates the way it does in a cap-weighted US index.
• Running since 2013, one of the original iShares single-factor funds rather than a recent launch.ishares.com

• XMMO Launched in 2005, it is one of the longest-running momentum ETFs listed in the US, and it runs the factor inside mid caps instead of the usual mega-cap universe.
• The rule is spelled out: S&P ranks momentum over 12 months while skipping the most recent one (dodging short-term reversals), adjusts the score for volatility, and rebalances in March and September.spglobal.com
• 0.34% a year puts it right at the going rate for a factor fund in its peer group, and it is a multi-billion-dollar fund with steady enough volume for everyday trading.
• It tracks its stated index closely and has held the same mandate for two decades, which lands it in the upper half of its factor cohort on implementation.

Worth knowing

• SIZE Thinly traded next to headline index funds, so bid-ask spreads can run wider and bigger orders need more care.
• This is a tilt, not a small-cap fund: the index draws from US large and mid caps and favors the smaller end of that pool.
• A mid-sized fund by category standards, not one of the asset-gathering giants. Pays quarterly.

• XMMO About 80 names out of a 400-stock parent index. That concentration cuts both ways, and sector weights can drift wherever momentum happens to be crowding.
• Momentum by design buys what has already climbed, and the list only resets twice a year, so the portfolio can sit with a fading trend between rebalances.spglobal.com
• Mid caps plus a momentum tilt is a bumpier ride than broad-market exposure, and cheaper factor options exist (SIZE at 0.15%, MGV at 0.05%).

Full SIZE profile⁠

Full XMMO profile⁠