IJH vs MDY: 99% overlap
iShares Core S&P Mid-Cap ETF and SPDR S&P MidCap 400 ETF Trust share 98.9% of their portfolios by weight — computed as Σ min(wA, wB) over every holding both funds own.
You would hold two tickers and get the diversification of 1.0. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
IJH and MDY hold 399 of the same securities. The ten contributing most to the overlap figure:
| Holding | in IJH | in MDY | Δ |
|---|---|---|---|
| FTI | 0.8% | 0.8% | 0.0% |
| CRS | 0.8% | 0.8% | 0.0% |
| ILMN | 0.8% | 0.8% | 0.0% |
| TWLO | 0.8% | 0.8% | 0.0% |
| CW | 0.8% | 0.8% | 0.0% |
| ATI | 0.8% | 0.8% | 0.0% |
| NVT | 0.7% | 0.7% | 0.0% |
| XPO | 0.7% | 0.7% | 0.0% |
| WWD | 0.7% | 0.7% | 0.0% |
| P | 0.7% | 0.7% | 0.0% |
Where IJH and MDY differ
Sector weights as a share of each fund, ordered by the size of the gap rather than the size of the sector — two funds that overlap heavily still usually diverge somewhere.
| Sector | IJH | MDY | Δ |
|---|---|---|---|
| Cash & Other | 0.0% | 1.1% | −1.1pp |
| Health Care | 10.0% | 9.7% | +0.3pp |
| Financials | 15.1% | 14.8% | +0.3pp |
| Industrials | 25.5% | 25.4% | +0.2pp |
| Cash and/or Derivatives | 0.1% | 0.0% | +0.1pp |
| Information Technology | 13.9% | 13.8% | +0.1pp |
| Consumer Discretionary | 10.3% | 10.2% | +0.1pp |
| Real Estate | 6.9% | 6.9% | +0.0pp |
Δ is IJH minus MDY, in percentage points. Sector data is not published by every issuer, so “Unclassified” is a real category rather than a gap in the table.
What each fund holds alone
0.5% of IJH by weight, held in no part of MDY.
0.0% of MDY by weight, held in no part of IJH.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| IJH | MDY | |
|---|---|---|
| Top 10 holdings | 7.6% | 7.6% |
| Positions held | 404 | 400 |
| Cost per $10,000 held, per year | $5 | $23 |
Cost is the expense ratio applied to $10,000; it excludes any brokerage commission, bid-ask spread or tax consequence. Figures are facts about the funds, not a suggestion about which to hold.
Frequently asked
How much do IJH and MDY overlap?
IJH and MDY overlap 98.9% by portfolio weight — they are effectively the same fund. They share 399 holdings. The figure comes from current issuer holdings files (IJH as of 2026-07-23, MDY as of 2026-07-23).
How is the overlap between IJH and MDY calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If IJH holds a stock at 6% and MDY holds the same stock at 4%, 4% counts as shared. The result is bounded between 0% and 100%, and it is computed after looking through any fund-of-funds to the underlying holdings.
Is it redundant to hold both IJH and MDY?
That depends on your goals — we state facts, not advice. At 98.9% overlap, most of what one fund holds, the other holds too. Expense ratios: IJH 0.05% versus MDY 0.23%.
What does IJH own that MDY doesn't?
IJH holds 404 positions and MDY holds 400; 4 of IJH's positions don't appear in MDY at all, and they are 0.5% of IJH by weight.
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Related comparisons
Sources: issuer holdings files, IJH as of 2026-07-23, MDY as of 2026-07-23. Weights are fractions of each fund. Diagnostics, not advice.