MDY vs VB: 43% overlap
SPDR S&P MidCap 400 ETF Trust and Vanguard Small-Cap ETF share 43.0% 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 1.6. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
MDY and VB hold 396 of the same securities. The ten contributing most to the overlap figure:
| Holding | in MDY | in VB | Δ |
|---|---|---|---|
| TWLO | 0.8% | 0.4% | 0.4% |
| MKSI | 0.6% | 0.4% | 0.3% |
| CRS | 0.8% | 0.3% | 0.5% |
| CW | 0.8% | 0.3% | 0.4% |
| NVT | 0.7% | 0.3% | 0.4% |
| ENTG | 0.6% | 0.3% | 0.2% |
| ATI | 0.8% | 0.3% | 0.4% |
| FTI | 0.8% | 0.3% | 0.5% |
| MTZ | 0.6% | 0.3% | 0.3% |
| MTSI | 0.5% | 0.3% | 0.2% |
Where MDY and VB 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 | MDY | VB | Δ |
|---|---|---|---|
| Industrials | 25.4% | 21.0% | +4.3pp |
| Information Technology | 13.8% | 16.1% | −2.3pp |
| Health Care | 9.7% | 11.9% | −2.3pp |
| Financials | 14.8% | 12.7% | +2.1pp |
| Cash and/or Derivatives | 0.0% | 1.7% | −1.7pp |
| Communication Services | 1.5% | 3.0% | −1.5pp |
| Energy | 4.9% | 3.7% | +1.2pp |
| Cash & Other | 1.1% | 0.0% | +1.1pp |
Δ is MDY minus VB, 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
0.6% of MDY by weight, held in no part of VB.
57.0% of VB by weight, held in no part of MDY.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| MDY | VB | |
|---|---|---|
| Top 10 holdings | 7.6% | 5.6% |
| Positions held | 400 | 1,308 |
| Cost per $10,000 held, per year | $23 | $3 |
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 MDY and VB overlap?
MDY and VB overlap 43.0% by portfolio weight — moderate overlap. They share 396 holdings. The figure comes from current issuer holdings files (MDY as of 2026-07-23, VB as of 2026-06-30).
How is the overlap between MDY and VB calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If MDY holds a stock at 6% and VB 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 MDY and VB?
That depends on your goals — we state facts, not advice. At 43.0% overlap, each fund still contributes meaningfully distinct exposure.
What does MDY own that VB doesn't?
MDY holds 400 positions and VB holds 1,308; 3 of MDY's positions don't appear in VB at all, and they are 0.6% of MDY by weight.
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Related comparisons
Sources: issuer holdings files, MDY as of 2026-07-23, VB as of 2026-06-30. Weights are fractions of each fund. Diagnostics, not advice.