CIK: 0001644956
Total reported value
$30.3B
Reporting period: 2026-03-31 · Number of holdings: 413
WILLIAM BLAIR INVESTMENT MANAGEMENT, LLC disclosed 413 holdings in its latest 13F filing for the period ending 2026-03-31, with total reported value of $30.3B and a quarterly turnover rate of 43.3%.
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William Blair Investment Management, LLC's disclosed holdings carry a Herfindahl concentration index of 0.015 — mathematically equivalent to about 68 equally-sized positions, well below its 413 actual disclosed holdings. That gap points to a strategy built around a small core of high-conviction bets rather than broad diversification.
Position sizes vary widely across the portfolio (a coefficient of variation of 2.25), with a handful of outsized bets alongside many smaller positions.
No strong tilt toward either adding to existing winners or initiating outsized new positions was observed in the latest reported quarter.
Trim MSFT
-17.0% -$615.7M
Trim ORCL
-95.6% -$236.7M
Trim AMZN
-27.9% -$353.7M
Trim MELI
-54.8% -$204.1M
Trim QTWO
-88.8% -$180.2M
Trim CHE
-99.8% -$147.2M
WILLIAM BLAIR is harvesting gains from mega-cap tech and redeploying into defensive pharma, signaling a deliberate shift from beta-chasing to capital preservation. The fund's zero momentum score confirms it is actively leaning against the AI narrative, not hedging but rotating.
This portfolio prices in a regime of multiple compression in growth stocks and a late-cycle rotation to defensives. The opposing thesis bets on sustained AI capex and a soft landing that keeps Big Tech earnings resilient, a scenario in which these trims would destroy relative returns.
The structural tension: a 40% Information Technology weighting remains even after trimming names like NVDA and MSFT. This is not a rotation but a partial profit-take that leaves the portfolio levered to the same crowded factor it claims to distrust, making it acutely vulnerable to both a tech unwind and the opportunity cost of standing against persistent momentum.
Compiled by AI from public 13F filings; reflects historical positioning only and carries no investment recommendation.
Showing top 200 holdings (of 413 total)
| # | Ticker | Issuer | Asset Subclass | Weight | Weight Change | Shares Change | 4Q Trend |
|---|---|---|---|---|---|---|---|
| 1 | TSM | Taiwan Semiconductor-sp Adr | Stock-Tech | 6.16% | — | -7.80% | |
| 2 | NVDA | Nvidia CORP | Stock-Tech | 5.15% | -0.38% | -15.87% | |
| 3 | AAPL | Apple INC | Stock-Tech | 4.04% | -0.09% | -11.61% | |
| 4 | MSFT | Microsoft CORP | Stock-Tech | 3.54% | -1.17% | -17.00% | |
| 5 | GOOGL | Alphabet Inc-cl A | Stock-Comm Services | 2.38% | -0.37% | -20.61% | |
| 6 | AVGO | Broadcom INC | Stock-Tech | 2.25% | -0.20% | -13.21% | |
| 7 | AMZN | Amazon.com INC | Stock-Consumer Disc | 2.18% | -0.64% | -27.89% | |
| 8 | META | Meta Platforms Inc-class A | Stock-Comm Services | 1.92% | -0.26% | -14.63% | |
| 9 | MA | Mastercard INC - A | Stock-Financials | 1.75% | +0.02% | -2.24% | |
| 10 | AZN | AstraZeneca PLC | Stock-Healthcare | 1.25% | +1.25% | NEW | |
| 11 | LIN | Linde plc | Stock-Materials | 1.04% | — | -1.11% | |
| 12 | CG | Carlyle Group Inc/the | Stock-Financials | 1.01% | -0.17% | -11.65% | |
| 13 | COST | Costco Wholesale CORP | Stock-Consumer Staples | 1.00% | — | -7.92% | |
| 14 | ITUB | Itau Unibanco H-spon Prf Adr | Stock-Financials | 0.88% | — | -13.32% | |
| 15 | TWST | Twist Bioscience CORP | Stock-Other | 0.83% | — | -11.50% | |
| 16 | NOW | Servicenow INC | Stock-Tech | 0.82% | — | +10.37% | |
| 17 | PRMB | Primo Brands CORP | Stock-Consumer Staples | 0.81% | — | +3.40% | |
| 18 | MLI | Mueller Industries INC | Stock-Industrials | 0.77% | — | +18.53% | |
| 19 | INTU | Intuit INC | Stock-Tech | 0.76% | — | +20.65% | |
| 20 | MNST | Monster Beverage CORP | Stock-Consumer Staples | 0.70% | — | -21.96% | |
| 21 | AMD | Advanced Micro Devices | Stock-Tech | 0.70% | — | -22.17% | |
| 22 | BAP | Credicorp Ltd. | Stock-Financials | 0.70% | — | -18.86% | |
| 23 | A | Agilent Technologies INC | Stock-Healthcare | 0.68% | — | -12.95% | |
| 24 | ORLY | O'reilly Automotive INC | Stock-Consumer Disc | 0.67% | — | -25.88% | |
| 25 | BWXT | Bwx Technologies INC | Stock-Industrials | 0.66% | — | -11.36% | |
| 26 | TRU | Transunion | Stock-Financials | 0.66% | -0.29% | -27.09% | |
| 27 | ONTO | Onto Innovation INC | Stock-Tech | 0.65% | — | -44.16% | |
| 28 | IDXX | Idexx Laboratories INC | Stock-Healthcare | 0.65% | -0.18% | -20.33% | |
| 29 | NXT | Nextpower Inc-cl A | Stock-Tech | 0.65% | — | +19.06% | |
| 30 | ARGX | Argenx Se - Adr | Stock-Healthcare | 0.64% | — | +18.96% | |
| 31 | CAVA | Cava Group INC | Stock-Consumer Disc | 0.64% | — | -1.04% | |
| 32 | LSCC | Lattice Semiconductor CORP | Stock-Tech | 0.63% | — | -3.84% | |
| 33 | FFIV | F5 INC | Stock-Tech | 0.62% | — | +18.12% | |
| 34 | AKAM | Akamai Technologies INC | Stock-Tech | 0.61% | +0.61% | NEW | |
| 35 | CCJ | Cameco CORP | Stock-Energy | 0.60% | — | -15.07% | |
| 36 | UNH | Unitedhealth Group INC | Stock-Healthcare | 0.60% | — | -11.67% | |
| 37 | MDGL | Madrigal Pharmaceuticals INC | Stock-Healthcare | 0.59% | — | -3.87% | |
| 38 | NU | Nu Holdings Ltd. | Stock-Financials | 0.58% | -0.29% | -34.40% | |
| 39 | GMED | Globus Medical INC - A | Stock-Healthcare | 0.57% | — | -20.24% | |
| 40 | CHRW | C.h. Robinson Worldwide INC | Stock-Industrials | 0.57% | +0.37% | +138.09% | |
| 41 | P | Everpure Inc-a | Stock-Tech | 0.56% | — | -23.02% | |
| 42 | SNOW | Snowflake INC | Stock-Tech | 0.56% | -0.26% | -16.29% | |
| 43 | TLN | Talen Energy CORP | Stock-Utilities | 0.55% | — | -7.76% | |
| 44 | LOPE | Grand Canyon Education INC | Stock-Consumer Staples | 0.55% | +0.34% | +116.21% | |
| 45 | EG | Everest Group, Ltd. | Stock-Financials | 0.55% | — | -13.37% | |
| 46 | HALO | Halozyme Therapeutics INC | Stock-Healthcare | 0.54% | — | +37.06% | |
| 47 | MLM | Martin Marietta Materials | Stock-Materials | 0.53% | — | +0.81% | |
| 48 | COHR | Coherent CORP | Stock-Tech | 0.53% | — | -23.47% | |
| 49 | CW | Curtiss-wright CORP | Stock-Industrials | 0.52% | — | -16.47% | |
| 50 | RRX | Regal Rexnord CORP | Stock-Industrials | 0.52% | — | +10.30% |
Performance for Q3 2026
+3.1%
Performance Last 4 Quarters
+17.6%
Based on 73% of reported portfolio value with available pricing
| Period | Holdings | Total value | Stability | Top holdings |
|---|---|---|---|---|
| 2026-03-31 | 413 | $30.3B | 43 | |
| 2025-12-31 | 413 | $35.9B | 30 | |
| 2025-09-30 | 414 | $38.7B | 49 | |
| 2025-06-30 | 417 | $37.7B | 0 | |
| 2025-03-31 | 423 | $35.6B | 100 | |
| 2024-12-31 | 433 | $40.9B | 0 | |
| 2024-09-30 | 412 | $40.5B | 0 | |
| 2024-06-30 | 411 | $38.1B | 0 | |
| 2024-03-31 | 410 | $38.7B | 0 | |
| 2023-12-31 | 406 | $34.4B | 0 | |
| 2023-09-30 | 398 | $30.1B | 0 | |
| 2023-06-30 | 395 | $31.2B | 0 | |
| 2023-03-31 | 393 | $28.7B | 0 | |
| 2022-12-31 | 401 | $26.1B | 0 | |
| 2022-09-30 | 387 | $25.3B | 0 | |
| 2022-06-30 | 403 | $27.0B | 0 | |
| 2022-03-31 | 441 | $33.5B | 0 | |
| 2021-12-31 | 427 | $37.0B | 0 | |
| 2021-09-30 | 431 | $35.5B | 0 | |
| 2021-06-30 | 465 | $31.9B | 100 | |
| 2021-03-31 | 367 | $30.9B | 26 | |
| 2020-12-31 | 356 | $30.0B | 30 | |
| 2020-09-30 | 343 | $25.7B | 24 | |
| 2020-06-30 | 341 | $24.6B | 40 | |
| 2020-03-31 | 339 | $20.5B | 40 | |
| 2019-12-31 | 356 | $25.1B | 25 | |
| 2019-09-30 | 357 | $23.4B | 24 | |
| 2019-06-30 | 372 | $23.8B | 29 | |
| 2019-03-31 | 406 | $23.8B | 29 | |
| 2018-12-31 | 404 | $20.1B | 49 | |
| 2018-09-30 | 419 | $28.9B | 26 | |
| 2018-06-30 | 476 | $26.9B | 30 | |
| 2018-03-31 | 432 | $26.2B | 32 | |
| 2017-12-31 | 427 | $25.7B | 32 | |
| 2017-09-30 | 434 | $27.9B | 25 | |
| 2017-06-30 | 448 | $27.5B | 25 | |
| 2017-03-31 | 433 | $26.5B | 32 | |
| 2016-12-31 | 435 | $25.0B | 35 | |
| 2016-09-30 | 443 | $26.4B | 30 | |
| 2016-06-30 | 451 | $25.3B | 29 | |
| 2016-03-31 | 450 | $25.2B | 35 | |
| 2015-12-31 | 444 | $24.7B | 100 | |
| 2015-09-30 | 1068 | $49.0B | — |
William Blair Investment Management, LLC's most significant position changes for 2026-03-31: New buy: AstraZeneca PLC (AZN); Sold out: Sea Ltd-adr (SE); New buy: Akamai Technologies INC (AKAM); Sold out: Waystar Holding CORP (WAY); New buy: Borgwarner INC (BWA).
| # | Ticker | Issuer | Weight Change | Shares Change | Action |
|---|---|---|---|---|---|
| 1 | STRL | Sterling Infrastructure INC | +0.4% | +683.97% | Add |
| 2 | CHRW | C.h. Robinson Worldwide INC | +0.4% | +138.09% | Add |
| 3 | LOPE | Grand Canyon Education INC | +0.3% | +116.21% | Add |
| 4 | TIGO | Millicom International Cellular S.A. | +0.3% | +1022.91% | Add |
| 5 | MA | Mastercard INC - A | 0% | -2.24% | Trim |
| 6 | AAPL | Apple INC | -0.1% | -11.61% | Trim |
| 7 | CG | Carlyle Group Inc/the | -0.2% | -11.65% | Trim |
| 8 | IDXX | Idexx Laboratories INC | -0.2% | -20.33% | Trim |
| 9 | AVGO | Broadcom INC | -0.2% | -13.21% | Trim |
| 10 | CIEN | Ciena CORP | -0.2% | -63.72% | Trim |
| 11 | META | Meta Platforms Inc-class A | -0.3% | -14.63% | Trim |
| 12 | SNOW | Snowflake INC | -0.3% | -16.29% | Trim |
| 13 | GRAB | Grab Holdings Limited | -0.3% | -83.65% | Trim |
| 14 | TRU | Transunion | -0.3% | -27.09% | Trim |
| 15 | NU | Nu Holdings Ltd. | -0.3% | -34.40% | Trim |
| 16 | DOCS | Doximity Inc-class A | -0.3% | -11.41% | Trim |
| 17 | GOOGL | Alphabet Inc-cl A | -0.4% | -20.61% | Trim |
| 18 | NVDA | Nvidia CORP | -0.4% | -15.87% | Trim |
| 19 | TYL | Tyler Technologies INC | -0.4% | -56.44% | Trim |
| 20 | BCO | Brink's Co/the | -0.4% | -78.42% | Trim |
| 21 | CHE | Chemed CORP | -0.4% | -99.78% | Trim |
| 22 | QTWO | Q2 Holdings INC | -0.5% | -88.79% | Trim |
| 23 | MELI | Mercadolibre INC | -0.5% | -54.80% | Trim |
| 24 | AMZN | Amazon.com INC | -0.6% | -27.89% | Trim |
| 25 | ORCL | Oracle CORP | -0.7% | -95.57% | Trim |
| 26 | MSFT | Microsoft CORP | -1.2% | -17.00% | Trim |
| 27 | AZN | AstraZeneca PLC | — | NEW | New buy |
| 28 | SE | Sea Ltd-adr | — | EXIT | Sold out |
| 29 | AKAM | Akamai Technologies INC | — | NEW | New buy |
| 30 | WAY | Waystar Holding CORP | — | EXIT | Sold out |
| 31 | BWA | Borgwarner INC | — | NEW | New buy |
| 32 | AM6 | Amicus Therapeutics INC | — | EXIT | Sold out |
| 33 | WAL | Western Alliance Bancorp | — | EXIT | Sold out |
| 34 | CWAN | Clearwater Analytics Holdings, Inc. | — | EXIT | Sold out |
| 35 | APH | Amphenol Corp-cl A | — | NEW | New buy |
| 36 | TER | Teradyne INC | — | EXIT | Sold out |
| 37 | POWI | Power Integrations INC | — | NEW | New buy |
| 38 | OWL | Blue Owl Capital INC | — | EXIT | Sold out |
| 39 | SYNA | Synaptics INC | — | NEW | New buy |
| 40 | EXLS | Exlservice Holdings INC | — | EXIT | Sold out |
| 41 | PEN | Penumbra INC | — | EXIT | Sold out |
| 42 | LFUS | Littelfuse INC | — | NEW | New buy |
| 43 | NBHC | National Bank Hold-cl A | — | NEW | New buy |
| 44 | BAM | Brookfield Asset Mgmt-a | — | EXIT | Sold out |
| 45 | BIRK | Birkenstock Holding plc | — | NEW | New buy |
| 46 | CADE | Cadence Bank | — | EXIT | Sold out |
| 47 | MZTI | Marzetti Company/the | — | EXIT | Sold out |
| 48 | KMT | Kennametal INC | — | NEW | New buy |
| 49 | GH | Guardant Health INC | — | NEW | New buy |
| 50 | CASY | Casey's General Stores INC | — | NEW | New buy |
| Period | Filed | Type | EDGAR |
|---|---|---|---|
| 2026-03-31 | 2026-05-08 | 13F-HR | View on EDGAR |
| 2025-12-31 | 2026-02-09 | 13F-HR | View on EDGAR |
| 2025-09-30 | 2025-11-12 | 13F-HR | View on EDGAR |
| 2025-06-30 | 2025-07-29 | 13F-HR | View on EDGAR |
| 2025-03-31 | 2025-05-09 | 13F-HR | View on EDGAR |
| 2024-12-31 | 2025-02-10 | 13F-HR | View on EDGAR |
| 2024-09-30 | 2024-11-08 | 13F-HR | View on EDGAR |
| 2024-06-30 | 2024-08-08 | 13F-HR | View on EDGAR |
| 2024-03-31 | 2024-05-08 | 13F-HR | View on EDGAR |
| 2023-12-31 | 2024-02-09 | 13F-HR | View on EDGAR |
| 2023-09-30 | 2023-11-09 | 13F-HR | View on EDGAR |
| 2023-06-30 | 2023-08-11 | 13F-HR | View on EDGAR |
| 2023-03-31 | 2023-05-12 | 13F-HR | View on EDGAR |
| 2022-12-31 | 2023-02-09 | 13F-HR | View on EDGAR |
| 2022-09-30 | 2022-11-09 | 13F-HR | View on EDGAR |
| 2022-06-30 | 2022-08-10 | 13F-HR | View on EDGAR |
| 2022-03-31 | 2022-05-11 | 13F-HR | View on EDGAR |
| 2021-12-31 | 2022-02-14 | 13F-HR | View on EDGAR |
| 2021-09-30 | 2021-11-10 | 13F-HR | View on EDGAR |
| 2021-06-30 | 2021-08-12 | 13F-HR | View on EDGAR |
| 2021-03-31 | 2021-05-13 | 13F-HR | View on EDGAR |
| 2020-12-31 | 2021-02-09 | 13F-HR | View on EDGAR |
| 2020-09-30 | 2020-11-06 | 13F-HR | View on EDGAR |
| 2020-06-30 | 2020-08-12 | 13F-HR | View on EDGAR |
| 2020-03-31 | 2020-05-08 | 13F-HR | View on EDGAR |
| 2019-12-31 | 2020-02-12 | 13F-HR | View on EDGAR |
| 2019-09-30 | 2019-11-12 | 13F-HR | View on EDGAR |
| 2019-06-30 | 2019-08-09 | 13F-HR | View on EDGAR |
| 2019-03-31 | 2019-05-10 | 13F-HR | View on EDGAR |
| 2018-12-31 | 2019-02-13 | 13F-HR | View on EDGAR |
| 2018-09-30 | 2018-11-13 | 13F-HR | View on EDGAR |
| 2018-06-30 | 2018-08-14 | 13F-HR | View on EDGAR |
| 2018-03-31 | 2018-05-14 | 13F-HR | View on EDGAR |
| 2017-12-31 | 2018-02-16 | Amendment | View on EDGAR |
| 2017-12-31 | 2018-02-14 | 13F-HR | View on EDGAR |
| 2017-09-30 | 2017-11-13 | 13F-HR | View on EDGAR |
| 2017-06-30 | 2017-08-04 | 13F-HR | View on EDGAR |
| 2017-03-31 | 2017-05-10 | 13F-HR | View on EDGAR |
| 2016-12-31 | 2017-02-14 | 13F-HR | View on EDGAR |
| 2016-09-30 | 2016-11-14 | 13F-HR | View on EDGAR |
| 2016-06-30 | 2016-08-08 | 13F-HR | View on EDGAR |
| 2016-03-31 | 2016-05-16 | 13F-HR | View on EDGAR |
| 2015-12-31 | 2016-02-16 | 13F-HR | View on EDGAR |
| 2015-09-30 | 2015-11-12 | 13F-HR | View on EDGAR |
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