Parties to the Stockholders Agreement

Exhibit 99.1

Parties to the Stockholders Agreement

1. Ameritrade Holding Corporation

2. Silver Lake Partners, L.P.

3. Silver Lake Investors, L.P.

4. Silver Lake Technology Investors, L.L.C.

5. TA/Advent VIII, L.P.

6. TA Executives Fund, LLC

7. TA Investors, LLC

8. TA Atlantic & Pacific IV, L.P.

9. TA IX, L.P.

10. Advent Atlantic & Pacific III, L.P.

11. J. Xxx Xxxxxxxx

12. Xxxxxxx X. Xxxxxxxx

13. Xxxxxxx X. Xxxxxxxx 1994 Dynasty Trust

14. J. Xxx Xxxxxxxx 1994 Dynasty Trust

15. Xxxxxxxx Grandchildren Trust