The EU Commission has adopted a draft bill aimed at improving gender balance in the boardrooms of major companies. The move comes after the EU\'s executive body found voluntary corporate efforts had failed. Most publicly listed companies in the European Union would have to ensure that, by 2020, at least 40 percent of their supervisory board members are women, according to the proposal drafted by EU Justice Commissioner Viviane Reding. \"It\'s done,\" Reding wrote Wednesday on Twitter, after successfully convincing fellow commissioners on the EU executive of the need for the quota. The draft forces companies to fill board vacancies with members of \"the under-represented sex\" if candidates are equally qualified. Reding\'s plan would affect about 5,000 corporations in the European Union, as companies with annual revenue lower than 50 million euros ($63.6 million) and employing less than 250 people are excluded from the bill. The draft is Reding\'s second attempt to introduce a quota for women, after a first draft was turned down by the Commission three weeks ago. Changes to the original draft provide for lower sanctions and penalties for companies not complying with the law. In addition, the quota law no longer applies to executive boards. In recent weeks, Viviane Reding has repeatedly said that she finds voluntary pledges made by corporations to be insufficient in view of only a slight increase in female board members last year. In 2011, the number of women on EU company boards edged up to 13.5 percent on average. The draft requires the approval of the European Parliament and the leaders of the EU\'s 27 member states. Fiercest resistance is expected from the governments of Sweden and Great Britain. In Germany, where 16 percent of board members are female, the upper house of parliament, the Bundesrat, recently condoned the quota, stepping up pressure on Chancellor Angela Merkel to support the EU Commission draft bill.