MGC vs SPY: Holdings Overlap
MGCVanguard Mega Cap Index Fund
Vanguard · 173 holdings · $10.3B · as of 2026-05-31
SPYState Street® SPDR® S&P 500® ETF Trust
State Street (SPDR) · 504 holdings · $812.0B · as of 2026-08-06
Holdings snapshots are 67 days apart (MGC: 2026-05-31, SPY: 2026-08-06). Weights and index membership change between snapshots, so the true current overlap is typically higher than shown. For funds tracking the same index, the gap can be 5–15 points.
How similar are MGC and SPY?
Vanguard Mega Cap Index Fund (MGC, by Vanguard) holds 173 positions; State Street® SPDR® S&P 500® ETF Trust (SPY, by State Street (SPDR)) holds 504. They have 169 holdings in common, and by portfolio weight the two funds are 81.6% identical. In practical terms the pair is heavily overlapping, with largely the same stocks driving both funds.
- Overlap by Weight
- 81.6%Sum of the smaller weight of each shared holding
- Shared Holdings
- 169MGC holds 173 · SPY holds 504
- Weight in Shared Holdings
- MGC 98%·SPY 82%Share of each fund's weight in stocks both funds own
Based on each fund's latest official holdings. How is this calculated?
What makes each fund different
Only in MGC
4 of 173 positions (1.6% of the fund) are not held by SPY.
Only in SPY
335 of 504 positions (17.4% of the fund) are not held by MGC. Showing the top 30 by weight.
Sector Breakdown
| Sector | MGC | SPY |
|---|---|---|
| Information Technology | 42.4% | 37.6% |
| Financials | 10.7% | 12.3% |
| Communication Services | 12.2% | 9.7% |
| Consumer Discretionary | 9.7% | 9.3% |
| Health Care | 8.6% | 8.9% |
| Other Sectors | 16.0% | 22.1% |
Share of each fund's portfolio weight by GICS-style sector, compiled from issuer fund data and our own classification of the holdings, not the issuers' published sector charts.
Performance
| Fund | 1M | YTD | 1Y | 3Y (ann.) | 5Y (ann.) | 10Y (ann.) | Yield |
|---|---|---|---|---|---|---|---|
| MGC | +3.6% | +13.6% | +24.3% | +22.7% | +14.0% | +16.2% | 0.89% |
| SPY | +3.4% | +14.0% | +23.7% | +21.2% | +13.3% | +15.3% | 0.97% |
Total returns including dividends, from adjusted daily closes as of 2026-08-07. 3Y/5Y/10Y are annualized. Yield is trailing-12-month distributions over the last close. Past performance does not predict future results.
Project the growth of $10,000 in MGC vs SPY →
Shared Holdings(169)
The top 10 shared positions account for 47% of the overlap, led by NVDA, AAPL and MSFT.
 NVDANVIDIA Corp. COM | 9.10% | 8.00% | 8.00% |
|---|---|---|---|
 AAPLApple Inc. COM | 8.55% | 6.92% | 6.92% |
 MSFTMicrosoft Corp. COM | 6.24% | 5.60% | 5.60% |
 AMZNAmazon.com, Inc. COM | 4.88% | 4.02% | 4.02% |
 GOOGLAlphabet Inc. CAP STK CL A | 4.13% | 3.16% | 3.16% |
 AVGOBroadcom Inc COM | 3.95% | 3.00% | 3.00% |
 GOOGAlphabet Inc. CAP STK CL C | 3.25% | 2.54% | 2.54% |
 METAMeta Platforms, Inc., Class A | 2.58% | 1.95% | 1.95% |
 MUMicron Technology Inc. COM | 2.04% | 1.50% | 1.50% |
 BRK-BBerkshire Hathaway, Inc., Class B | 1.53% | 1.45% | 1.45% |
 LLYEli Lilly & Co. COM | 1.75% | 1.42% | 1.42% |
 JPMJPMorgan Chase & Co. COM | 1.41% | 1.44% | 1.41% |
 TSLATesla Inc COM | 2.29% | 1.36% | 1.36% |
 AMDAdvanced Micro Devices Inc. COM | 1.57% | 1.20% | 1.20% |
 JNJJohnson & Johnson COM | 1.01% | 0.93% | 0.93% |
 VVisa, Inc., Class A | 1.02% | 0.93% | 0.93% |
 WMTWalmart Inc COM | 0.95% | 0.74% | 0.74% |
 CSCOCisco Systems, Inc. COM | 0.80% | 0.72% | 0.72% |
 INTCIntel Corporation COM | 0.86% | 0.71% | 0.71% |
 MAMasterCard Incorporated CL A | 0.73% | 0.70% | 0.70% |
 ABBVAbbVie Inc. COM | 0.72% | 0.65% | 0.65% |
 COSTCostco Wholesale Corporation COM | 0.79% | 0.63% | 0.63% |
 AMATApplied Materials Inc. COM | 0.67% | 0.63% | 0.63% |
 BACBank of America Corp. COM | 0.62% | 0.62% | 0.62% |
 CATCaterpillar Inc COM | 0.76% | 0.59% | 0.59% |
Frequently Asked Questions
How much do MGC and SPY overlap?
MGC and SPY overlap by 81.6% of portfolio weight. They share 169 holdings (MGC holds 173 positions and SPY holds 504), based on each fund's latest SEC-reported holdings.
Is it redundant to own both MGC and SPY?
The two portfolios are 81.6% identical by weight. Owning both mostly doubles down on the shared core rather than diversifying: the same large positions drive both funds.
What are the biggest shared holdings of MGC and SPY?
The largest positions held by both funds are NVDA, AAPL, MSFT, AMZN and GOOGL. Together the top 10 shared positions account for 47% of the total overlap.
What does MGC own that SPY doesn't?
4 positions (1.6% of MGC) are unique to MGC, led by XOM, HON and BRK-A. In the other direction, 335 positions (17.4% of SPY) are unique to SPY.