OEF vs MGC: Holdings Overlap
iShares · 101 holdings · $20.4B · as of 2026-03-31
MGCVanguard Mega Cap Index Fund
Vanguard · 173 holdings · $10.3B · as of 2026-05-31
Holdings snapshots are 61 days apart (OEF: 2026-03-31, MGC: 2026-05-31). 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 OEF and MGC?
iShares S&P 100 ETF (OEF, by iShares) holds 101 positions; Vanguard Mega Cap Index Fund (MGC, by Vanguard) holds 173. They have 100 holdings in common, and by portfolio weight the two funds are 84.6% identical. In practical terms the pair is heavily overlapping, with largely the same stocks driving both funds.
- Overlap by Weight
- 84.6%Sum of the smaller weight of each shared holding
- Shared Holdings
- 100OEF holds 101 · MGC holds 173
- Weight in Shared Holdings
- OEF 100%·MGC 88%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 OEF
1 of 101 positions (0.2% of the fund) are not held by MGC.
GMGeneral Motors Company COM0.17%
Only in MGC
73 of 173 positions (12.2% of the fund) are not held by OEF. Showing the top 30 by weight.
Sector Breakdown
| Sector | OEF | MGC |
|---|---|---|
| Information Technology | 38.9% | 42.4% |
| Communication Services | 13.5% | 12.2% |
| Financials | 11.2% | 10.7% |
| Consumer Discretionary | 10.2% | 9.7% |
| Health Care | 9.3% | 8.6% |
| Other Sectors | 16.7% | 16.0% |
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 |
|---|---|---|---|---|---|---|---|
| OEF | +4.0% | +12.2% | +23.1% | +23.3% | +14.9% | +16.5% | 0.84% |
| MGC | +3.6% | +13.6% | +24.3% | +22.7% | +14.0% | +16.2% | 0.89% |
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 OEF vs MGC →
Shared Holdings(100)
The top 10 shared positions account for 55% of the overlap, led by NVDA, AAPL and MSFT.
 NVDANVIDIA Corp. COM | 10.50% | 9.10% | 9.10% |
|---|---|---|---|
 AAPLApple Inc. COM | 9.23% | 8.55% | 8.55% |
 MSFTMicrosoft Corp. COM | 6.81% | 6.24% | 6.24% |
 AMZNAmazon.com, Inc. COM | 5.04% | 4.88% | 4.88% |
 GOOGLAlphabet Inc. CAP STK CL A | 4.15% | 4.13% | 4.13% |
 AVGOBroadcom Inc COM | 3.63% | 3.95% | 3.63% |
 GOOGAlphabet Inc. CAP STK CL C | 3.32% | 3.25% | 3.25% |
 METAMeta Platforms, Inc., Class A | 3.10% | 2.58% | 2.58% |
 TSLATesla Inc COM | 2.59% | 2.29% | 2.29% |
 LLYEli Lilly & Co. COM | 1.81% | 1.75% | 1.75% |
 BRK-BBerkshire Hathaway, Inc., Class B | 2.18% | 1.53% | 1.53% |
 JPMJPMorgan Chase & Co. COM | 1.96% | 1.41% | 1.41% |
 XOMExxon Mobil Corp. COM | 1.76% | 1.13% | 1.13% |
 VVisa, Inc., Class A | 1.26% | 1.02% | 1.02% |
 JNJJohnson & Johnson COM | 1.46% | 1.01% | 1.01% |
 WMTWalmart Inc COM | 1.35% | 0.95% | 0.95% |
 MUMicron Technology Inc. COM | 0.94% | 2.04% | 0.94% |
 AMDAdvanced Micro Devices Inc. COM | 0.82% | 1.57% | 0.82% |
 COSTCostco Wholesale Corporation COM | 1.10% | 0.79% | 0.79% |
 CATCaterpillar Inc COM | 0.82% | 0.76% | 0.76% |
 CSCOCisco Systems, Inc. COM | 0.76% | 0.80% | 0.76% |
 MAMasterCard Incorporated CL A | 1.01% | 0.73% | 0.73% |
 ABBVAbbVie Inc. COM | 0.95% | 0.72% | 0.72% |
 NFLXNetflix, Inc. COM | 1.01% | 0.68% | 0.68% |
 AMATApplied Materials Inc. COM | 0.67% | 0.67% | 0.67% |
Frequently Asked Questions
How much do OEF and MGC overlap?
OEF and MGC overlap by 84.6% of portfolio weight. They share 100 holdings (OEF holds 101 positions and MGC holds 173), based on each fund's latest SEC-reported holdings.
Is it redundant to own both OEF and MGC?
The two portfolios are 84.6% 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 OEF and MGC?
The largest positions held by both funds are NVDA, AAPL, MSFT, AMZN and GOOGL. Together the top 10 shared positions account for 55% of the total overlap.
What does OEF own that MGC doesn't?
1 positions (0.2% of OEF) are unique to OEF, led by GM. In the other direction, 73 positions (12.2% of MGC) are unique to MGC.