ITOT vs MDY: how much do they overlap?
iShares Core S&P Total U.S. Stock Market ETF (ITOT) · SPDR S&P MIDCAP 400 ETF Trust (MDY)
overlap by weight · 399 shared holdings
ITOT: 2470 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
ITOT 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 ITOT | in MDY |
|---|---|---|---|
| TechnipFMC plc | FTI | 0.04% | 0.78% |
| United Therapeutics Corp. | UTHR | 0.04% | 0.65% |
| Curtiss-Wright Corp. | CW | 0.04% | 0.78% |
| XPO, Inc. | XPO | 0.04% | 0.68% |
| Woodward, Inc. | WWD | 0.03% | 0.67% |
| Royal Gold, Inc. | RGLD | 0.03% | 0.45% |
| US Foods Holding Corp. | USFD | 0.03% | 0.61% |
| Burlington Stores, Inc. | BURL | 0.03% | 0.56% |
| MasTec, Inc. | MTZ | 0.03% | 0.66% |
| ATI, Inc. | ATI | 0.03% | 0.71% |
FAQ
How much do ITOT and MDY overlap?
ITOT and MDY have a 5.1% overlap by weight, sharing 399 holdings (out of 2470 in ITOT and 400 in MDY), based on official issuer holdings as of 2026-03-31.
What does 5.1% overlap mean?
ITOT and MDY hold mostly different stocks. Combining them genuinely spreads your exposure across different parts of the market.
Which stocks do ITOT and MDY both hold?
The largest shared positions are TechnipFMC plc, United Therapeutics Corp., Curtiss-Wright Corp., XPO, Inc., Woodward, Inc.. The full list of top shared holdings with weights in each fund is shown on this page.