Reviewed November 16, 2026 (Korea). This study compares public Form 13F positions for the quarters ended March 31 and June 30, 2026.
Was the fixed 17-manager panel’s positive Q2 valuation effect spread broadly across its continuing issuers? Not evenly. Seven issuer groups supplied half of the $72.94 billion gross positive valuation effect, and the top ten supplied 62.22%. Yet no single issuer dominated: Apple was the largest at 11.17%, while an absolute-effect concentration index implies about 24.55 equally sized issuer contributors. The result is concentrated enough that a short list matters, but broader than a one-stock explanation.
This is a second-stage analysis of our Q1-to-Q2 quantity-versus-valuation bridge. That study found a net $61.16 billion valuation component across 1,396 clean continuous manager–security observations. Here we aggregate those observation-level effects to 1,067 normalized issuer groups, combine multiple share classes where the preserved mapping identifies one issuer, and ask which companies generated the result. “Valuation effect” is a quarter-end arithmetic component—not a manager return, profit or cash flow.
Three findings
- Seven issuer groups produced half of the gross positive valuation effect. The top ten supplied 62.22%; Apple alone supplied 11.17%.
- The result was not only Berkshire Hathaway. Excluding Berkshire, seven issuers still produced half of the positive effect and the top-ten share was 61.46%, although the leaders shifted toward Micron, SanDisk and semiconductor equipment.
- Breadth by issuer count was misleading. The 863 issuer groups held continuously by only one manager supplied just 2.59% of the net valuation effect; issuers held by two to four managers supplied 58.30%, and 13 issuers held by at least five managers supplied 39.11%.
Positive marks were concentrated, but not in one name
| Issuer-concentration measure | All 17 managers | Excluding Berkshire |
|---|---|---|
| Continuous issuer groups | 1,067 | 1,062 |
| Gross positive valuation effect | $72.94bn | $41.36bn |
| Gross negative valuation effect | −$11.78bn | −$3.00bn |
| Net valuation effect | +$61.16bn | +$38.37bn |
| Largest positive issuer share | 11.17% | 12.25% |
| Top-five share of positive effect | 41.31% | 44.12% |
| Top-ten share of positive effect | 62.22% | 61.46% |
| Issuer groups needed for 50% | 7 | 7 |
| Effective issuers by absolute effect | 24.55 | 23.10 |
The distinction between gross and net is important. Positive issuer effects totaled $72.94 billion, while negative issuer effects offset $11.78 billion, leaving the $61.16 billion net component. Dividing a positive leader by the net would overstate its share because the denominator already includes negative offsets. We therefore rank positive contributors against gross positive effects and use absolute effects for the concentration index.
The effective-issuer count compresses the unequal absolute effects into an equivalent equal-weight count. An HHI of 0.04074 produces 24.55 effective issuers, far below the 1,067 issuer groups present in the clean continuous sample. That gap says most issuer rows were economically small for this particular Q1-to-Q2 valuation bridge. It does not say they were unimportant to each manager’s strategy, nor does it measure total portfolio diversification.
The ten largest positive issuer effects
| Issuer | Continuous managers | Valuation effect | Share of gross positive effect |
|---|---|---|---|
| Apple (AAPL) | 4 | $8.15bn | 11.17% |
| Alphabet (GOOG/GOOGL) | 11 | $7.36bn | 10.10% |
| American Express (AXP) | 2 | $5.42bn | 7.44% |
| Micron Technology (MU) | 5 | $5.07bn | 6.95% |
| SanDisk (SNDK) | 3 | $4.13bn | 5.66% |
| Bank of America (BAC) | 2 | $4.11bn | 5.64% |
| Lam Research (LRCX) | 5 | $3.46bn | 4.75% |
| Taiwan Semiconductor (TSM) | 11 | $3.00bn | 4.11% |
| Applied Materials (AMAT) | 3 | $2.59bn | 3.55% |
| Coca-Cola (KO) | 3 | $2.09bn | 2.87% |
The table mixes two different forms of influence. Apple, American Express, Bank of America and Coca-Cola were large partly because of Berkshire’s position sizes. Alphabet, Micron, Lam Research and Taiwan Semiconductor combined large effects with wider representation across the panel. That is why a pure ranking by issuer dollars cannot answer whether the result was a shared market move or one manager’s portfolio structure.
The largest positive effects also show why higher reported value should not be called buying. The symmetric bridge holds average shares against the change in quarter-end implied unit value. A manager can report fewer shares and still contribute a positive valuation effect. Our earlier headcount-versus-reported-value study demonstrated the same warning from a different angle: manager direction and value direction can disagree inside a widely held issuer.
Many single-manager issuers contributed little to the net result
| Continuous-holder breadth | Issuer groups | Net valuation effect | Share of net effect | Share of gross absolute effect |
|---|---|---|---|---|
| 1 manager | 863 | +$1.58bn | 2.59% | 16.19% |
| 2–4 managers | 191 | +$35.66bn | 58.30% | 55.31% |
| 5+ managers | 13 | +$23.92bn | 39.11% | 28.50% |
| Total | 1,067 | +$61.16bn | 100.00% | 100.00% |
The 863 single-manager issuer groups look broad by count, but positive and negative effects largely offset, leaving only $1.58 billion of net contribution. The middle breadth bucket supplied the largest net amount. The 13 issuer groups held continuously by at least five managers supplied $23.92 billion even though they were only 1.2% of issuer groups.
That does not establish consensus conviction. A manager can hold the same issuer for different reasons, with different share-count changes and different portfolio weights. This calculation only shows that quarter-end valuation effects for the more widely represented continuing issuers were large in aggregate. The relevant 5+ group included Alphabet, Micron, Lam Research, Taiwan Semiconductor, AMD, Amazon, NVIDIA, Broadcom, ASML, Microsoft, DoorDash, Uber and Meta.
Removing Berkshire changes the names, not the concentration conclusion
Berkshire accounted for 63.28% of the comparable Q2 value in the underlying bridge, so we repeat the issuer calculation without it. The gross positive effect falls from $72.94 billion to $41.36 billion, but the concentration pattern barely changes: seven issuers still reach 50%, the top ten supply 61.46%, and the effective-issuer count is 23.10.
The leadership changes materially. Without Berkshire, the five largest positive effects are Micron ($5.07 billion), SanDisk ($4.13 billion), Lam Research ($3.46 billion), Taiwan Semiconductor ($3.00 billion) and Applied Materials ($2.59 billion). Alphabet falls to $1.70 billion because most of its all-panel effect came through Berkshire’s two share classes. The sensitivity therefore separates two claims: Berkshire changes which issuers lead, but it does not explain why a short issuer list supplies most of the positive valuation effect.
The negative side is more Berkshire-sensitive. Occidental Petroleum (−$4.35 billion) and Chevron (−$3.47 billion) together supplied 66.43% of the all-panel gross negative valuation effect. Removing Berkshire reduces the gross negative effect from $11.78 billion to $3.00 billion. That is another reason to show positive, negative and net figures separately rather than describing the $61.16 billion net as one broad market move.
Method and reconciliation
- Panel: Berkshire Hathaway; Pershing Square; Dalal Street; Appaloosa; Greenlight/DME; Fundsmith; Third Point; the Icahn reporting group; Soros Fund Management; Bridgewater; ARK; Tiger Global; Coatue; Altimeter; Whale Rock; Situational Awareness; and Light Street. Congressional filers are excluded.
- Periods: quarter ends March 31 and June 30, 2026. The source set contains 35 official SEC information tables because Pershing Square’s Q1 comparison uses two complementary reporting entities.
- Eligible observations: 1,396 clean continuous manager–security observations reported in shares. The same manager and exact CUSIP must appear in both quarters after preserved corporate-action controls.
- Issuer aggregation: observation-level valuation effects are summed to the normalized issuer key. Multiple share classes can combine when the mapping identifies one issuer; a manager counts once per issuer.
- Valuation effect: (Q2 implied unit value − Q1 implied unit value) × average adjusted share count. It is the midpoint component from the prior exact reconciliation.
- Concentration: positive shares use gross positive effects. HHI uses absolute issuer effects; effective issuers equal 1/HHI. Signed net-effect shares are used only for the breadth table.
- Corporate actions: Q1 shares were adjusted for issuer-verified forward splits in Booking Holdings, KLA and Carvana. ARK/CrowdStrike, Icahn/IEP and Situational Awareness/Applied Digital remain quarantined from the clean bridge.
The issuer-level aggregation reconciles to the observation-level bridge within less than one millionth of a dollar in floating-point presentation. The calculation retains full-dollar source values. Displayed billions and percentages are rounded only after aggregation.
Why this still uses Q1 and Q2
The SEC’s current calendar sets the Q3 2026 Form 13F deadline at November 16, 2026. This article’s research cutoff is November 16, 2026, 12:10 a.m. Korea time—still November 15 in the United States and before the filing deadline. A deadline is not a complete matched dataset. We preserve the verified Q1-to-Q2 panel and will move the study forward only after all required Q3 reporting entities, amendments and related-manager relationships are checked.
Limits
Form 13F is a quarter-end disclosure of reportable securities, shares and fair market value. It does not reveal transaction dates, execution prices, motives, short positions, non-13F assets or a complete live portfolio. The valuation component is not a manager return: it is an arithmetic bridge between two reported snapshots. Pooled dollars are not unique AUM because the same issuer can be counted once for each reporting group. The exact-CUSIP continuity requirement excludes new, no-longer-reported and identifier-changing positions, so this study does not describe the entire change in each portfolio.
Issuer mapping is a research normalization layer. It merges Alphabet’s two listed share classes but does not collapse unrelated securities simply because names look similar. Breadth refers only to the fixed 17-manager sample and cannot be generalized to the investment industry. This analysis is for information and education, not investment advice. For manager histories and the full statistical series, use the AHNIM Studio Guru hub.
Three findings to retain
- Seven issuer groups supplied half of the $72.94 billion gross positive Q1-to-Q2 valuation effect; the top ten supplied 62.22%.
- Excluding Berkshire changed the leaders but not the concentration result: seven issuers still reached half and the top-ten share was 61.46%.
- Single-manager issuers were 863 of 1,067 issuer groups but supplied only 2.59% of the net valuation effect; the economically important effects were concentrated in shared and mid-breadth names.
Sources and original documents
Accessed November 15–16, 2026. AHNIM Studio owns the eligibility screen, issuer mapping, corporate-action controls, midpoint decomposition, concentration calculations and sensitivity analysis.
- SEC, Frequently Asked Questions About Form 13F (reporting fields, fair value, deadlines and amendments).
- SEC, Form 13F and instructions.
- Berkshire Hathaway: Q1 · Q2.
- Pershing Square: Q1 reporting entity · Q1 combination report · Q2.
- Dalal Street: Q1 · Q2.
- Appaloosa: Q1 · Q2.
- Greenlight / DME: Q1 · Q2.
- Fundsmith: Q1 · Q2.
- Third Point: Q1 · Q2.
- Icahn reporting group: Q1 · Q2.
- Soros Fund Management: Q1 · Q2.
- Bridgewater: Q1 · Q2.
- ARK: Q1 · Q2.
- Tiger Global: Q1 · Q2.
- Coatue: Q1 · Q2.
- Altimeter: Q1 · Q2.
- Whale Rock: Q1 · Q2.
- Situational Awareness: Q1 · Q2.
- Light Street: Q1 · Q2.
- Corporate-action controls: Booking Holdings 25-for-1 split; KLA 10-for-1 split; Carvana 5-for-1 split filing.