QuickLinks -- Click here to rapidly navigate through this document

Exhibit 10.1

NINTH AMENDMENT
TO THE JANUS CAPITAL GROUP INC.
401(k), PROFIT SHARING AND EMPLOYEE STOCK OWNERSHIP PLAN

        The Janus Capital Group Inc. 401(k), Profit Sharing and Employee Stock
Ownership Plan, as restated effective November 1, 2001 (the "Plan") is hereby
amended as follows, effective January 1, 2006, with respect to participants who
remain employees on such January 1:

1.Section 1.33 of the Plan hereby is amended in its entirety with the following
paragraph:

1.33  Vested Percentage and Vesting Schedule

A Participant's Vested Percentage as of a given date will be that percentage
determined in accordance with the following Vesting Schedule:

Years of Service

--------------------------------------------------------------------------------

  Vested Percentage

--------------------------------------------------------------------------------

  Less than 1   0 % At least 1, but less than 2   20 % At least 2, but less than
3   40 % At least 3, but less than 4   60 % At least 4, but less than 5   80 % 5
or more   100 %

Notwithstanding the preceding, and provided the Participant is an Employee on
the date next described, a Participant will be 100% vested upon reaching his
Normal Retirement Age, becoming eligible for Disability Retirement as defined in
Section 7.03 or his death.

Notwithstanding the above, the Vested Percentage of a Participant whose accounts
from a prior plan have been transferred to this Plan pursuant to Section 8.06
will not be less than his vested percentage determined under the provisions of
the prior plan.

Notwithstanding the foregoing provisions of this Section 1.33, the Accrued
Benefit of each Participant who terminates employment with the Employer on
account of a Job Elimination (defined below) shall be fully vested and 100%
nonforfeitable. For purposes of this Section 1.33, "Job Elimination" shall mean
the termination of a Participant's employment with all Employers as a result of
the elimination of the Participant's position in the group, division, department
or branch in which the Participant works, because of a corporate transaction or
reorganization, outsourcing, technology change, reduced work volume or another
business reason. A Participant's termination of employment with the Employers is
not on account of a Job Elimination if the Participant's employment is
terminated due to death, disability, voluntary termination of employment, or any
involuntary termination of employment initiated by an Employer for cause,
inadequate job performance or any other reason that results in the Participant's
position remaining open to be filled by a new hire.

2.Section 3.03 of the Plan hereby is amended by deleting the first paragraph of
subsection (a), and replacing it with the following:

Employer Matching Contributions Account means the Account of a Participant
reflecting Employer Matching contributions, forfeitures, investment income or
loss allocated thereto and distributions. A Participant's Employer Matching
Contributions Account is 100% vested at all times.

--------------------------------------------------------------------------------

3.Except as amended above, the Plan shall remain in full force and effect.

        IN WITNESS WHEREOF, Janus Capital Group Inc. has executed this Ninth
Amendment as of this 23rd day of October, 2005.

    Janus Capital Group Inc.
 
 
By:
/s/  JOHN H. BLUHER      

--------------------------------------------------------------------------------

ATTEST:    
/s/  CURT R. FOUST      

--------------------------------------------------------------------------------

 
 

2

--------------------------------------------------------------------------------

QuickLinks

Exhibit 10.1