William Blair & Company
MEC icon

William Blair & Company’s Mayville Engineering Co MEC Stock Holding History

William Blair & Company’s Portfolio MEC Stock Details MEC Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q1 		$10.1M Sell
565,300
-18,459
-3% -$355K 0.03% 348
2025
Q4 		$10.9M Buy
583,759
+206,549
+55% +$3.37M 0.03% 341
2025
Q3 		$5.19M Buy
377,210
+3,762
+1% +$56.6K 0.01% 507
2025
Q2 		$5.96M Buy
373,448
+281,198
+305% +$4.02M 0.02% 456
2025
Q1 		$1.24M Sell
92,250
-105,490
-53% -$1.59M ﹤0.01% 827
2024
Q4 		$3.11M Buy
197,740
+39,278
+25% +$718K 0.01% 615
2024
Q3 		$3.34M Buy
158,462
+1,273
+0.8% +$23.8K 0.01% 593
2024
Q2 		$2.62M Buy
157,189
+12,299
+8% +$186K 0.01% 633
2024
Q1 		$2.08M Sell
144,890
-99
-0.1% -$1.29K 0.01% 666
2023
Q4 		$2.09M Sell
144,989
-50,395
-26% -$625K 0.01% 660
2023
Q3 		$2.14M Sell
195,384
-9,774
-5% -$113K 0.01% 636
2023
Q2 		$2.56M Sell
205,158
-3,489
-2% -$44.1K 0.01% 610
2023
Q1 		$3.11M Buy
+208,647
New +$3.04M 0.01% 545

Other funds holding MEC

Allspring Global Investments
Allspring Global Investments Charlotte, North Carolina $59.7B AUM 29.08% 1-Year Est. Return
Dimensional Fund Advisors
Dimensional Fund Advisors Austin, Texas $481B AUM 30.42% 1-Year Est. Return
BlackRock
BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return
PCM
Portolan Capital Management Boston, Massachusetts $1.88B AUM 115.74% 1-Year Est. Return
RA
Royce & Associates New York $10.1B AUM 42.88% 1-Year Est. Return
ER
EVR Research Richmond, Virginia $250M AUM 41.5% 1-Year Est. Return
VCM
Vanguard Capital Management Malvern, Pennsylvania $4.04T AUM
First Eagle Investment Management
First Eagle Investment Management New York $59B AUM 32.99% 1-Year Est. Return
GIM
Granahan Investment Management Waltham, Massachusetts $2.07B AUM 56.45% 1-Year Est. Return
Millennium Management
Millennium Management New York $240B AUM 35.51% 1-Year Est. Return

William Blair & Company's MEC Position: Q1 2026 in Review

William Blair & Company reduced its Mayville Engineering Co (MEC) stake by 3.2% in Q1 2026, selling an estimated $355K and leaving 565,300 shares worth $10.1M. The position accounts for 0.03% of the portfolio, ranked #348.

William Blair & Company first reported a position in MEC in Q1 2023 and has held it in 13 quarters since. The position peaked at $10.9M in Q4 2025. 124 funds tracked by Wall St. Rank hold MEC as of Q1 2026.

  • William Blair & Company held 565,300 shares of Mayville Engineering Co worth $10.1M as of Q1 2026.
  • William Blair & Company sold 18,459 Mayville Engineering Co shares in Q1 2026, an estimated $355K.
  • Mayville Engineering Co made up 0.03% of William Blair & Company's portfolio in Q1 2026, its #348 holding.
  • William Blair & Company first reported a position in Mayville Engineering Co in Q1 2023 and has held it in 13 quarters since.
  • William Blair & Company's Mayville Engineering Co position peaked at $10.9M in Q4 2025.
  • 124 funds tracked by Wall St. Rank held Mayville Engineering Co as of Q1 2026.

Based on William Blair & Company's 13F filing for Q1 2026, filed 8 May 2026.