Proportion of women still modest

An average rating of the supervisory bodies based on German school grades resulted in an overall grade of 2.3 for 2015, compared to 2.9 in 2011 (2014: 2.4; 2013: 2.6; 2012: 2.7).

The German blue chips are also making good progress with the women's quota adopted by the Bundestag in March. Thanks to nine newly elected women, the proportion of female shareholder representatives rose significantly from 21.1% to 23.7%, despite three women dropping out.

This corresponds to a women's quota of 39 percent for the successors - compared to 34 percent in 2014. Including the 2015 Annual General Meetings, 13 committees on the owners' side have already achieved the required women's quota of 30 percent.

Based on the regular expiring mandates and in compliance with the legal requirements, six boards will catch up in 2016.

Despite the positive trend described above, there are still significant differences between the genders in terms of supervisory board membership in DAX 30 companies:

At 3.6 compared to 6.5 years, women have an average length of service that is three years shorter. At 52.6 years, they are around four years younger than their male colleagues (56.4 years) when they take up office.

The average age of male supervisory board members is 62.9 years, which is more than six years older than their female counterparts (56.2 years).

Diversity promotes growth

The study shows a significant correlation between excellently composed supervisory boards and above-average growth.

"The statistical correlation between supervisors' historical ratings and reported growth rates supports our thesis that more diversified supervisory boards promote a more expansive corporate strategy.

In recent years, we have mostly seen cleverly thought-out personnel changes that take into account both the desirable breadth of experience and the required diversity considerations"

says Jens-Thomas Pietralla, Managing Director at Russell Reynolds Associates and responsible for the DAX 30 Supervisory Board Study.

Who has the most mandates

Michael Diekmann and former SAP CEO Henning Kagermann hold the most supervisory board mandates at DAX companies, with four each.

Ex-Co-CEO Jim Hagemann Snabe holds three DAX Supervisory Board positions and two more in his home country of Denmark. A total of 16 DAX board members hold supervisory board mandates in other DAX companies.

That is two fewer than in the previous year. Lufthansa proves to be particularly well connected with three current DAX board members on the supervisory board.