IWB vs MGC: Holdings Overlap
iShares · 1005 holdings · $49.9B · 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 (IWB: 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 IWB and MGC?
iShares Russell 1000 ETF (IWB, by iShares) holds 1005 positions; Vanguard Mega Cap Index Fund (MGC, by Vanguard) holds 173. They have 172 holdings in common, and by portfolio weight the two funds are 76.1% identical. In practical terms the pair is heavily overlapping, with largely the same stocks driving both funds.
- Overlap by Weight
- 76.1%Sum of the smaller weight of each shared holding
- Shared Holdings
- 172IWB holds 1005 · MGC holds 173
- Weight in Shared Holdings
- IWB 77%·MGC 100%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 IWB
833 of 1005 positions (22.8% of the fund) are not held by MGC. Showing the top 30 by weight.
Sector Breakdown
| Sector | IWB | MGC |
|---|---|---|
| Information Technology | 30.9% | 42.4% |
| Financials | 12.9% | 10.7% |
| Communication Services | 10.2% | 12.2% |
| Consumer Discretionary | 10.0% | 9.7% |
| Industrials | 9.9% | 6.4% |
| Other Sectors | 26.0% | 18.1% |
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 |
|---|---|---|---|---|---|---|---|
| IWB | +3.4% | +13.9% | +23.1% | +20.9% | +12.6% | +15.0% | 0.89% |
| 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 IWB vs MGC →
Shared Holdings(172)
The top 10 shared positions account for 44% of the overlap, led by NVDA, AAPL and MSFT.
 NVDANVIDIA Corp. COM | 6.81% | 9.10% | 6.81% |
|---|---|---|---|
 AAPLApple Inc. COM | 6.10% | 8.55% | 6.10% |
 MSFTMicrosoft Corp. COM | 4.58% | 6.24% | 4.58% |
 AMZNAmazon.com, Inc. COM | 3.33% | 4.88% | 3.33% |
 GOOGLAlphabet Inc. CAP STK CL A | 2.79% | 4.13% | 2.79% |
 AVGOBroadcom Inc COM | 2.39% | 3.95% | 2.39% |
 GOOGAlphabet Inc. CAP STK CL C | 2.27% | 3.25% | 2.27% |
 METAMeta Platforms, Inc., Class A | 2.08% | 2.58% | 2.08% |
 TSLATesla Inc COM | 1.75% | 2.29% | 1.75% |
 BRK-BBerkshire Hathaway, Inc., Class B | 1.47% | 1.53% | 1.47% |
 JPMJPMorgan Chase & Co. COM | 1.33% | 1.41% | 1.33% |
 LLYEli Lilly & Co. COM | 1.23% | 1.75% | 1.23% |
 XOMExxon Mobil Corp. COM | 1.20% | 1.13% | 1.13% |
 JNJJohnson & Johnson COM | 0.98% | 1.01% | 0.98% |
 WMTWalmart Inc COM | 0.90% | 0.95% | 0.90% |
 VVisa, Inc., Class A | 0.85% | 1.02% | 0.85% |
 COSTCostco Wholesale Corporation COM | 0.74% | 0.79% | 0.74% |
 NFLXNetflix, Inc. COM | 0.68% | 0.68% | 0.68% |
 MAMasterCard Incorporated CL A | 0.67% | 0.73% | 0.67% |
 CVXChevron Corp. COM | 0.65% | 0.65% | 0.65% |
 ABBVAbbVie Inc. COM | 0.64% | 0.72% | 0.64% |
 MUMicron Technology Inc. COM | 0.63% | 2.04% | 0.63% |
 PGThe Procter & Gamble Co. COM | 0.57% | 0.62% | 0.57% |
 CATCaterpillar Inc COM | 0.55% | 0.76% | 0.55% |
 AMDAdvanced Micro Devices Inc. COM | 0.55% | 1.57% | 0.55% |
Frequently Asked Questions
How much do IWB and MGC overlap?
IWB and MGC overlap by 76.1% of portfolio weight. They share 172 holdings (IWB holds 1005 positions and MGC holds 173), based on each fund's latest SEC-reported holdings.
Is it redundant to own both IWB and MGC?
The two portfolios are 76.1% 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 IWB and MGC?
The largest positions held by both funds are NVDA, AAPL, MSFT, AMZN and GOOGL. Together the top 10 shared positions account for 44% of the total overlap.
What does IWB own that MGC doesn't?
833 positions (22.8% of IWB) are unique to IWB, led by VRT, HWM and WDC. In the other direction, 1 positions (0.1% of MGC) are unique to MGC.