BLAIR WILLIAM & CO/IL
SEC Form 13F institutional filer · CIK 0000902367
13F-HR · 487 reported holdings · 2026-03-31
Wealth management firm.
Reported long-US-equity value
$28.37B
Top-10 concentration
32.6%
BLAIR WILLIAM & CO/IL — $28.4B AUM allocation strategy
BLAIR WILLIAM & CO/IL files SEC Form 13F and reports $28.4B of long US equity value across 487 reported holdings for 2026-03-31.
Its largest sector bet is Information Technology 14.3%, followed by Financials 7.4% and Communication Services 7.0%.
The top 10 holdings account for 33% of reported value — a broadly spread portfolio. The sector and industry splits below are of the same reported value. Track quarter-over-quarter adds, trims, new positions and exits below — sourced from SEC 13F filings, public domain.
BLAIR WILLIAM & CO/IL — latest SEC 13F insights
Reported long-US-equity value (13F AUM)
$28.4B
total across 487 reported holdings · 2026-03-31 · excludes shorts, cash, non-US
Top-10 concentration
33% of value
higher = narrower conviction; lower = spread / hedging
Biggest adds (shares)
+$IVZ +1.18M sh · +$221M+$TECH +636K sh · +$31.7M+$MDLZ +446K sh · +$27.1M
Biggest trims (shares)
−$CSGP −1.12M sh · −$99.7M−$UBER −808K sh · −$98.3M−$WDAY −575K sh · −$145M
Exited to nil (held last quarter, gone now)
$BRO ($1.88M last qtr)$RVTY ($569K last qtr)$DVA ($342K last qtr)$FOX ($262K last qtr)$LVS ($247K last qtr)
Sector allocation (share of reported value)
each slice is a share of the reported long-US-equity value — smaller sectors and the rest of the book roll into “Other holdings”
Qtr shift = share-point change vs the prior quarter's filing — first period tracked for this filer; the column fills in with the next quarterly refresh.
Industry allocation (share of reported value)
- Interactive Media & Services7.0%—
- Technology Hardware, Storage & Peripherals5.3%—
- Systems Software4.5%—
- Broadline Retail4.4%—
- Transaction & Payment Processing Services3.6%—
- Semiconductors3.3%—
- Diversified Banks2.4%—
- Heavy Electrical Equipment2.1%—
- Other holdings67.3%—
the finer GICS cut of the same book — same denominator — smaller industries roll into “Other holdings”
Qtr shift = share-point change vs the prior quarter's filing — first period tracked for this filer; the column fills in with the next quarterly refresh.
Top S&P 500 holdings
9 of 9 rows · sorted by Value ↓
| Ticker | Holding | Shares | Value | Δ QoQ | Weight |
|---|---|---|---|---|---|
| $AAPL | Apple Inc | 5.93M | $1.51B | -19K | 5.3% |
| $MSFT | Microsoft Corporation | 3.5M | $1.29B | -76.5K | 4.6% |
| $AMZN | Amazon.com Inc | 6.06M | $1.26B | -6.49K | 4.4% |
| $NVDA | NVIDIA Corporation | 5.43M | $947M | -66.5K | 3.3% |
| $GOOGL | Alphabet Inc | 3.04M | $871M | -83K | 3.1% |
| $GOOG | Alphabet Inc. Class C Capital Stock | 2.44M | $701M | -57.5K | 2.5% |
| $JPM | JP Morgan Chase & Co | 2.32M | $680M | -847 | 2.4% |
| $GEV | GE Vernova Inc | 665K | $580M | +12.3K | 2.0% |
| $V | Visa Inc | 1.84M | $558M | -84.7K | 2.0% |
…and 478 more holdings in the full 13F filing (top positions only shown).
SEC Form 13F data sets · public domain · 45-day filing lag · >$100M AUM managers · as reported
← All 13F filers·← QuantOrb.pro
How to read Δ QoQ — the five insight categories, and the caveats
The categories. Analysts, quants and retail traders look past total portfolio value to isolate actionable signals. Five categories matter.
Conviction & concentration shifts
New positions vs complete exits — a brand-new stock signals high conviction; a full liquidation suggests a broken thesis or tax-loss harvesting. Aggressive sizing — look at share count, not dollars: a 20% share increase during a drawdown is strong dip-buying. Concentration — a narrowing top-5/10 means conviction; spreading capital across more names means hedging.
Sector & macro allocation rotations
Aggregating Δ QoQ moves across sectors shows where smart money is leaning in or sneaking out — rotating out of growth into defensives or energy, for example. The fund's total long equity exposure quarter-over-quarter is a proxy for overall institutional risk appetite.
Crowding & smart-money consensus
When several managers initiate or expand the same stock in the same quarter, that is institutional consensus. Contrarian reads: top pickers buying hard into a beaten-down name the market is selling.
Derivative & option overlays
Reported call/put changes indicate whether managers are adding downside hedges or leveraging upside exposure. Note: a long increase may be half of a market-neutral pair trade.
Who reads this
| Retail "cloners" | High-conviction ideas to replicate ~45 days after quarter-end. |
| Corporate IR | Which funds bought or dumped the stock, before the next call. |
| Quant / algo traders | Cross-sectional factor inputs: flow, momentum, ownership. |
Four caveats before you trade on it
- 45-day lag — holdings are quarter-end; positions may already be closed.
- Long-only — 13Fs miss shorts, pair trades and cash.
- No non-US / fixed income — the picture is US equities plus options.
- Corporate actions — splits and spinoffs distort raw share deltas.
Newsletter signup
Free subscription. Daily trading day morning dispatch. No spam.