IBKR
Interactive Brokers Group Inc
Interactive Brokers Group Inc historical holders
total: 11
Cantillon Capital Management Interactive Brokers Group Inc transactions over time
- Total transactions:
- 36
- New positions:
- 1
- Added:
- 12
- Reduced:
- 23
- Held since:
- 2017 Q2
- Held for:
- 36 quarters
- Latest activity:
- 2026 Q1
William Von Mueffling has been an institutional investor in Interactive Brokers Group Inc (IBKR) since 2017 Q2. According to 2026 Q1 report, William Von Mueffling holds 11,245,881 shares with a market value of roughly $754.26M representing 5.01% of their equity portfolio. The fund/company first acquired IBKR in 2017 Q2, initially purchasing about 7.70M shares. Since the initial investment, Cantillon Capital Management has made 35 more transactions in this position.
Does William Von Mueffling still hold IBKR?
Yes, William Von Mueffling continues to hold Interactive Brokers Group Inc (IBKR). According to their 2026 Q1 report, they maintain a position of 11,245,881 shares valued at approximately $754.26M, representing 5.01% of their equity portfolio.
When did William Von Mueffling first invest in IBKR?
William Von Mueffling first invested in Interactive Brokers Group Inc (IBKR) in 2017 Q2 at the reported quarter-end price of $9.36 per share, acquiring 7,703,564 shares in their initial purchase.
What is William Von Mueffling's average cost basis for IBKR?
Based on historical transaction data, William Von Mueffling's estimated cost basis for Interactive Brokers Group Inc (IBKR) is approximately $14.17 per share. This represents their average reported price* across all buy transactions.
Estimated cost basis*
- Weighted AVG buy price:
- $14.17
- Weighted AVG sell price:
- $35.03
IBKR transactions history by Cantillon Capital Management
36 results
| Period |
% of portfolio |
Shares held after* |
Reported price* |
Value* |
% (shares) of activity |
% change to portfolio |
|---|---|---|---|---|---|---|
|
2026 Q1
|
5.01%
|
11,245,881
|
$67.07
|
$754,261,239
|
-11.87% (-1,514,023)
|
-0.55%
|
|
2025 Q4
|
4.44%
|
12,759,904
|
$64.31
|
$820,589,426
|
+0.76% (+95,878)
|
+0.03%
|
|
2025 Q3
|
4.80%
|
12,664,026
|
$68.81
|
$871,411,630
|
-1.09% (-139,605)
|
-0.06%
|
|
2025 Q2
|
4.10%
|
12,803,631
|
$55.41
|
$709,449,194
|
-2.82% (-371,673)
|
-0.13%
|
|
2025 Q1
|
3.53%
|
13,175,304
|
$41.40
|
$545,424,647
|
-3.00% (-407,456)
|
-0.1%
|
|
2024 Q4
|
3.63%
|
13,582,760
|
$44.17
|
$599,916,552
|
+0.53% (+72,188)
|
+0.02%
|
|
2024 Q3
|
2.88%
|
13,510,572
|
$34.84
|
$470,708,328
|
-2.90% (-403,728)
|
-0.09%
|
|
2024 Q2
|
2.85%
|
13,914,300
|
$30.65
|
$426,473,295
|
-4.85% (-708,516)
|
-0.14%
|
|
2024 Q1
|
2.57%
|
14,622,816
|
$27.93
|
$408,378,694
|
-1.96% (-292,660)
|
-0.05%
|
|
2023 Q4
|
2.07%
|
14,915,476
|
$20.72
|
$309,123,240
|
-2.38% (-363,040)
|
-0.06%
|
|
2023 Q3
|
2.45%
|
$21.64
|
-0.39% (-59,356)
|
|||
|
2023 Q2
|
2.23%
|
$20.77
|
+6.38% (+920,272)
|
|||
|
2023 Q1
|
2.42%
|
$20.64
|
+11.93% (+1,536,744)
|
|||
|
2022 Q4
|
1.97%
|
$18.09
|
+30.33% (+2,997,368)
|
|||
|
2022 Q3
|
1.43%
|
$15.98
|
-0.88% (-88,156)
|
|||
|
2022 Q2
|
1.14%
|
$13.75
|
+12.07% (+1,073,632)
|
|||
|
2022 Q1
|
1.05%
|
$16.48
|
+2.87% (+248,044)
|
|||
|
2021 Q4
|
1.13%
|
$19.85
|
-7.02% (-653,304)
|
|||
|
2021 Q3
|
0.99%
|
$15.59
|
-1.41% (-132,992)
|
|||
|
2021 Q2
|
1.04%
|
$16.43
|
-1.59% (-152,848)
|
|||
|
2021 Q1
|
1.27%
|
$18.26
|
-3.27% (-324,572)
|
|||
|
2020 Q4
|
1.13%
|
$15.23
|
-0.40% (-40,104)
|
|||
|
2020 Q3
|
1.01%
|
$12.08
|
-1.02% (-102,544)
|
|||
|
2020 Q2
|
0.91%
|
$10.44
|
+0.75% (+75,172)
|
|||
|
2020 Q1
|
1.19%
|
$10.79
|
-0.29% (-28,592)
|
|||
|
2019 Q4
|
1.08%
|
$11.66
|
-2.07% (-211,084)
|
|||
|
2019 Q3
|
1.34%
|
$13.44
|
-0.72% (-73,624)
|
|||
|
2019 Q2
|
1.41%
|
$13.55
|
-1.72% (-180,092)
|
|||
|
2019 Q1
|
1.44%
|
$12.97
|
-0.77% (-81,128)
|
|||
|
2018 Q4
|
1.74%
|
$13.66
|
+0.90% (+94,380)
|
|||
|
2018 Q3
|
1.63%
|
$13.83
|
+5.73% (+567,152)
|
|||
|
2018 Q2
|
1.72%
|
$16.10
|
-2.66% (-270,828)
|
|||
|
2018 Q1
|
1.94%
|
$16.81
|
+24.57% (+2,004,764)
|
|||
|
2017 Q4
|
1.43%
|
$14.80
|
-4.93% (-422,848)
|
|||
|
2017 Q3
|
1.12%
|
$11.26
|
+11.42% (+879,496)
|
|||
|
2017 Q2
|
0.90%
|
$9.36
|
new
|
|||
* Shares, change to shares, sold shares, shares held after: split-adjusted.
* Reported price: this doesn't represent the actual buy or sell price. It is the split-adjusted price of the security as of the last day of the reported period.
If the security is completely sold out, we show the reported split-adjusted price prior to the actual period.
If the security is completely sold out, we show the reported split-adjusted price prior to the actual period.
* Estimated cost basis: based on "Reported price*" (not earlier than 2013 Q2). Calculation starts from the latest "new buy" activity to the latest "close out" activity (if any).
* Value or Price: If the security is completely sold out, we show the reported value (or price) prior to the actual period.
* New buy or own: this means there is no earlier reporting (for us or in general). So we can't know if the actual purchase of the security happened at the reported period or earlier.