Question 1

How many shares of IBKR does CANTILLON CAPITAL MANAGEMENT LLC own?

Accepted Answer

As of 2026-Q1, CANTILLON CAPITAL MANAGEMENT LLC holds 11.2M shares of IBKR (INTERACTIVE BROKERS GROUP IN).

Question 2

What is CANTILLON CAPITAL MANAGEMENT LLC's IBKR position worth?

Accepted Answer

As of 2026-Q1, CANTILLON CAPITAL MANAGEMENT LLC's IBKR position is worth $754.3M.

Question 3

Is CANTILLON CAPITAL MANAGEMENT LLC buying or selling IBKR?

Accepted Answer

In 2026-Q1, CANTILLON CAPITAL MANAGEMENT LLC decreased their IBKR position (-11.9% change in shares).

Question 4

When did CANTILLON CAPITAL MANAGEMENT LLC first buy IBKR?

Accepted Answer

Based on available 13F filings, CANTILLON CAPITAL MANAGEMENT LLC first reported a position in IBKR in 2026-Q1. They have held the position across 29 quarters.