They are less worried when the appointment has come from within, as it is expected that the firm will have a good knowledge of the candidate's capabilities.
Currently, men fill the majority of CEO positions in the Fortune 500 companies. It is not surprising that most tend to believe that they have the appropriate capabilities for executive positions.
When a woman is appointed CEO, observers will tend to see this as unusual and companies will need to justify the appointment more than they would for men.
Press coverage of female CEOs tends to focus on extraneous issues such as family more than with male appointments. The use of these stereotypes will decline when it becomes more commonplace to see women filling executive roles.
SHE'-E-OS: gender effects and investor reactions to the announcements of top executive appointments
Peggy M Lee and Erika Hayes James
Strategic Management Journal, Vol 28 No 3, March 2007