IWM vs MDY: how much do they overlap?
iShares Russell 2000 ETF (IWM) · SPDR S&P MIDCAP 400 ETF Trust (MDY)
overlap by weight · 95 shared holdings
IWM: 1934 holdings (as of 2026-03-31) · MDY: 400 holdings (as of 09-Jul-2026)
Note: the two funds' latest official filings have different dates, which can understate overlap slightly for funds tracking similar indexes.
Low overlap
What this means
IWM and MDY hold mostly different stocks. Combining them genuinely spreads your exposure across different parts of the market.
Overlap by weight sums the smaller of the two funds' weights for every stock they both hold — it answers "how much of my money is in the same stocks either way?" See methodology.
Top shared holdings
| Company | Ticker | in IWM | in MDY |
|---|---|---|---|
| Fabrinet | FN | 0.64% | 0.48% |
| Nextpower, Inc. | NXT | 0.6% | 0.46% |
| Coeur Mining, Inc. | CDE | 0.65% | 0.46% |
| Sterling Infrastructure, Inc. | STRL | 0.41% | 0.6% |
| TTM Technologies, Inc. | TTMI | 0.34% | 0.43% |
| Dycom Industries, Inc. | DY | 0.34% | 0.36% |
| Advanced Energy Industries, Inc. | AEIS | 0.41% | 0.33% |
| Rambus, Inc. | RMBS | 0.32% | 0.34% |
| SPX Technologies, Inc. | SPXC | 0.33% | 0.3% |
| Hecla Mining Co. | HL | 0.4% | 0.29% |
FAQ
How much do IWM and MDY overlap?
IWM and MDY have a 17.4% overlap by weight, sharing 95 holdings (out of 1934 in IWM and 400 in MDY), based on official issuer holdings as of 2026-03-31.
What does 17.4% overlap mean?
IWM and MDY hold mostly different stocks. Combining them genuinely spreads your exposure across different parts of the market.
Which stocks do IWM and MDY both hold?
The largest shared positions are Fabrinet, Nextpower, Inc., Coeur Mining, Inc., Sterling Infrastructure, Inc., TTM Technologies, Inc.. The full list of top shared holdings with weights in each fund is shown on this page.