William Blair & Company’s Byline Bancorp BY Stock Holding History

William Blair & Company’s Portfolio BY Stock Details BY Fund Activity

Bought

Maintained

Sold

Quarter	Market Value	Status	Shares	Change in Stake	Trade Value	Portfolio Weight	Portfolio Position
2026 Q1	$2.4M	Sell	75,986 -6,953	-8%	-$218K	0.01%	679
2025 Q4	$2.42M	Buy	82,939 +3,815	+5%	+$107K	0.01%	697
2025 Q3	$2.19M	Buy	79,124 +71,401	+925%	+$1.99M	0.01%	710
2025 Q2	$206K	Buy	+7,723	New	+$198K	﹤0.01%	1413
2021 Q4	–	Sell	-16,200	Closed	-$398K	–	1974
2021 Q3	$398K	Sell	16,200 -7,826	-33%	-$187K	﹤0.01%	1246
2021 Q2	$544K	Buy	24,026 +9,025	+60%	+$202K	﹤0.01%	1125
2021 Q1	$317K	Sell	15,001 -3,889	-21%	-$72.9K	﹤0.01%	1305
2020 Q4	$292K	Buy	18,890 +3,890	+26%	+$56.6K	﹤0.01%	1280
2020 Q3	$169K	Hold	15,000	–	–	﹤0.01%	1346
2020 Q2	$197K	Sell	15,000 -5,000	-25%	-$57.2K	﹤0.01%	1248
2020 Q1	$207K	Hold	20,000	–	–	﹤0.01%	1155
2019 Q4	$391K	Sell	20,000 -25,176	-56%	-$460K	﹤0.01%	1084
2019 Q3	$808K	Sell	45,176 -22,813	-34%	-$413K	﹤0.01%	811
2019 Q2	$1.3M	Buy	67,989 +47,989	+240%	+$920K	0.01%	695
2019 Q1	$370K	Hold	20,000	–	–	﹤0.01%	1066
2018 Q4	$333K	Hold	20,000	–	–	﹤0.01%	1050
2018 Q3	$454K	Hold	20,000	–	–	﹤0.01%	989
2018 Q2	$447K	Hold	20,000	–	–	﹤0.01%	983
2018 Q1	$459K	Hold	20,000	–	–	﹤0.01%	949
2017 Q4	$459K	Hold	20,000	–	–	﹤0.01%	993
2017 Q3	$425K	Hold	20,000	–	–	﹤0.01%	988
2017 Q2	$401K	Buy	+20,000	New	+$401K	﹤0.01%	1057

Other funds holding BY

BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return

Dimensional Fund Advisors Austin, Texas $481B AUM 30.42% 1-Year Est. Return

VCM

Vanguard Capital Management Malvern, Pennsylvania $4.04T AUM

State Street Boston, Massachusetts $2.9T AUM 29.55% 1-Year Est. Return

Wellington Management Group Boston, Massachusetts $535B AUM 26.23% 1-Year Est. Return

Boston Partners Boston, Massachusetts $95.5B AUM 28.4% 1-Year Est. Return

American Century Companies Kansas City, Missouri $194B AUM 35% 1-Year Est. Return

Fidelity Investments Boston, Massachusetts $1.9T AUM 41.92% 1-Year Est. Return

Geode Capital Management Boston, Massachusetts $1.61T AUM 30.72% 1-Year Est. Return

ACB

Aristotle Capital Boston Boston, Massachusetts $1.61B AUM 19.82% 1-Year Est. Return

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

William Blair & Company reduced its Byline Bancorp (BY) stake by 8.4% in Q1 2026, selling an estimated $218K and leaving 75,986 shares worth $2.4M. The position accounts for 0.01% of the portfolio, ranked #679.

William Blair & Company first reported a position in BY in Q2 2017 and has held it in 22 quarters since. The position peaked at $2.42M in Q4 2025. 188 funds tracked by Wall St. Rank hold BY as of Q1 2026.

William Blair & Company held 75,986 shares of Byline Bancorp worth $2.4M as of Q1 2026.
William Blair & Company sold 6,953 Byline Bancorp shares in Q1 2026, an estimated $218K.
Byline Bancorp made up 0.01% of William Blair & Company's portfolio in Q1 2026, its #679 holding.
William Blair & Company first reported a position in Byline Bancorp in Q2 2017 and has held it in 22 quarters since.
William Blair & Company's Byline Bancorp position peaked at $2.42M in Q4 2025.
188 funds tracked by Wall St. Rank held Byline Bancorp as of Q1 2026.

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