Data as of Sep 12, 2026. Both funds on the fields they both publish, from the same sources.
IBB vs MGK: how they differ
IBB and MGK hold 1% of their weight in the same names, and IBB returned more over the year.
iShares Biotechnology ETF and Vanguard Mega Cap Growth Index Fund.
What they hold in common
By the books each fund has filed, IBB and MGK hold 1% of their money in the same securities at the same weight.
| Holding | IBB | MGK |
|---|---|---|
| Vertex Pharmaceuticals, Inc. | 8.09% | 0.60% |
| Only in IBB | Only in MGK |
|---|---|
| Amgen, Inc. 7.84% | NVIDIA Corp 13.29% |
| Gilead Sciences, Inc. 6.85% | Apple Inc 12.19% |
| Regeneron Pharmaceuticals, Inc. 4.91% | Microsoft Corp 7.52% |
| Argenx SE 3.76% | Alphabet Inc 5.93% |
| Alnylam Pharmaceuticals, Inc. 3.12% | Alphabet Inc 4.67% |
| Natera, Inc. 2.89% | Amazon.com Inc 4.47% |
| Revolution Medicines, Inc. 2.78% | Broadcom Inc 4.28% |
| Biogen, Inc. 2.47% | Meta Platforms Inc 4.08% |
Weight overlap is an ETFIQ calculation: for every security both funds hold, the smaller of the two weights, summed. Above 50%, holding both is close to holding one of them twice. Holdings dated Jun 30, 2026.
| IBB iShares Biotechnology ETF | MGK Vanguard Mega Cap Growth Index Fund | |
|---|---|---|
| Where it sits | Core index fund | Core index fund |
| Issuer | iShares | Vanguard |
| What it is | Biotechnology | Mega Cap Growth |
| Total return, 1 year | +41.5% | +14.9% |
| S&P 500 over the same days | +17.5% | +17.5% |
| Gap to the S&P 500 | +24.0 pts | −2.6 pts |
| Expense ratio | 0.44% | 0.07% |
| Already in the S&P 500 | 35.6% | 99.2% |
| Holdings | 248 | 56 |
IBB in plain words
IBB is an index equity fund tracking the Biotechnology. Over the year to Sep 11, 2026 it returned +41.5% with distributions reinvested, against +17.5% for the S&P 500 and +23.0% for the Nasdaq-100. The prospectus expense ratio is 0.44% a year. By its holdings filed for Jun 30, 2026, 36% of the fund by weight is stocks the S&P 500 also holds, across 248 positions, with the top ten at 44.8%. It sat 6.5% below its high of Aug 19, 2026 on Sep 11, 2026.
MGK in plain words
MGK is an index equity fund tracking the Mega Cap Growth. Over the year to Sep 11, 2026 it returned +14.9% with distributions reinvested, against +17.5% for the S&P 500 and +23.0% for the Nasdaq-100. The prospectus expense ratio is 0.07% a year. By its holdings filed for Jun 30, 2026, 99% of the fund by weight is stocks the S&P 500 also holds, across 56 positions, with the top ten at 63.8%.
Questions people ask
- Which returned more over the last year, IBB or MGK?
- In the year to Sep 12, 2026, with distributions reinvested, IBB returned +41.5% and MGK returned +14.9%, so IBB returned more. One year is one year; the longer windows are in the table.
- Which is cheaper, IBB or MGK?
- IBB charges 0.44% a year and MGK charges 0.07%, so MGK is cheaper. Fees come from each fund's prospectus.
- How much do IBB and MGK overlap with the S&P 500?
- By their latest filed holdings, 36% of IBB and 99% of MGK by weight is stocks the S&P 500 already holds. Between the two funds, 1% of their books are the same securities at the same weight.
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Where these figures came from
ETFIQ links to the documents behind every figure. It is not affiliated with any issuer, and a link is not an endorsement.
Cite this page. ETFIQ, IBB against MGK, data as of Sep 12, 2026. https://etfiq.com/compare/any/IBB-MGK Free to use with attribution; the underlying files are at Open data.
A comparison is not a recommendation. Standards and sources