Data as of .
ARKK vs IDEF: which is really different?
ARKK and IDEF hold 7% of their weight in the same names, and ARKK returned more over the year.
ETFIQ Off-Index Score: IDEF scores higher
How much of it is not the index it is sold as an alternative to?
A percentile among the 349 thematic ETFs with a holdings filing. It is a position in a set, not a rating, and neither end of it is a recommendation. All thematic ETFs ranked by it · How it is computed
7% of the two portfolios are the same securities at the same weight.
What they hold in common
By the books each fund has filed, ARKK and IDEF hold 7% of their money in the same securities at the same weight.
| Only in ARKK | Only in IDEF |
|---|---|
| TESLA INC 9.75% | RTX 6.72% |
| SPACE EXPLORATION TECHN-CL A 6.52% | PALANTIR TECHNOLOGIES CLASS A 4.71% |
| CIRCLE INTERNET GROUP INC 5.56% | LOCKHEED MARTIN CORP 3.62% |
| TEMPUS AI INC-CL A 4.83% | BOEING 3.32% |
| CRISPR THERAPEUTICS AG 4.52% | ROLLS-ROYCE HOLDINGS PLC 3.30% |
| COINBASE GLOBAL INC -CLASS A 4.47% | GENERAL DYNAMICS CORP 2.97% |
| ROBINHOOD MARKETS INC - A 4.18% | USD CASH 2.72% |
| TWIST BIOSCIENCE CORP 3.29% | THALES SA 2.61% |
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 Sep 10, 2026 and Sep 11, 2026.
Performance, window by window
| Window | Total return | vs the S&P 500 | vs the Nasdaq-100 | |||
|---|---|---|---|---|---|---|
| ARKK | IDEF | ARKK | IDEF | ARKK | IDEF | |
| 3 months | +10.5% | −1.9% | +7.2 pts | −5.2 pts | +11.3 pts | −1.1 pts |
| 6 months | +19.0% | −8.5% | +3.0 pts | −24.5 pts | −1.7 pts | −29.2 pts |
| 1 year | +6.7% | +4.9% | −10.8 pts | −12.6 pts | −16.2 pts | −18.1 pts |
| 3 years | +89.9% | not published | +12.0 pts | not published | −5.2 pts | not published |
| Since launch | +353.4% | +26.5% | −8.3 pts | −6.4 pts | −318.1 pts | −13.6 pts |
| ARKK ARK Innovation ETF Holds 47 stocks in broad innovation and megatrends, 38% of its weight in S&P 500 companies | IDEF iShares Defense Industrials Active ETF Holds 152 stocks in defense, 36% of its weight in S&P 500 companies | |
|---|---|---|
| Issuer | ARK | iShares |
| Theme | Broad innovation and megatrends | Defense |
| In the S&P 500 | 38.1% | 36.1% |
| Active share vs the S&P 500 | 85.0% | 95.9% |
| In the Nasdaq-100 | 28.6% | 8.5% |
| Holdings | 47 | 152 |
| Top ten, share of the fund | 49.4% | 35.2% |
| Expense ratio | 0.75% | not published |
| Fee for the differing part | 0.88% | not published |
| Total return, 1 year | +6.7% | +4.9% |
| vs the S&P 500 | −10.8 pts | −12.6 pts |
| vs the Nasdaq-100 | −16.2 pts | −18.1 pts |
| Below its high | −45.9% | −13.9% |
ARKK in plain words
By weight, 38% of ARKK's portfolio is stocks that are also in the S&P 500; its active share against the S&P 500 is 85%. The top ten holdings are 49% of the fund across 47 positions, as published by its issuer for Sep 11, 2026. Over the year to Sep 11, 2026 the fund returned +6.7% with distributions reinvested against +17.5% for the S&P 500, so a holder was behind by 10.8 pts. It sits 45.9% below its all-time high of Feb 12, 2021.
IDEF in plain words
By weight, 36% of IDEF's portfolio is stocks that are also in the S&P 500; its active share against the S&P 500 is 96%. The top ten holdings are 35% of the fund across 152 positions, as published by its issuer for Sep 10, 2026. Over the year to Sep 11, 2026 the fund returned +4.9% with distributions reinvested against +17.5% for the S&P 500, so a holder was behind by 12.6 pts. It sits 13.9% below its all-time high of Mar 2, 2026.
Questions people ask
- Do ARKK and IDEF hold the same stocks?
- By their latest filings, 7% of their books are the same securities at the same weight, which is mostly different names. Overlap is the sum of the smaller weight of every security they share.
- Which is more different from the S&P 500, ARKK or IDEF?
- ARKK has 38% of its weight in S&P 500 names and IDEF has 36%, so IDEF differs more from the index.
Other comparisons
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, ARKK against IDEF, data as of Sep 11, 2026. https://etfiq.com/compare/themes/ARKK-IDEF Free to use with attribution; the underlying files are at Open data.