Fidelity, the $2.2 trillion asset manager, has walked out of a Jamie Dimon-led effort to create a code of best practice for US boardrooms, underscoring divisions among the world's top investors over corporate governance.

The move is a blow to months-long efforts led by Mr Dimon, chairman and chief executive of JP Morgan Chase, to draw up a blueprint for how boards should conduct themselves and engage with shareholders. The effort involves the leaders of the largest asset management firms and investors such as Warren Buffett. More recently it has expanded to include several big US companies, including General Electric, General Motors and Verizon.

Its aim has been to take some of the heat out of corporate governance controversies by persuading the biggest US shareholder groups to agree common standards and to promote long-term planning by companies.

However, Abigail Johnson, Fidelity's chief executive, decided not to sign up to a draft statement of principles, according to people involved. Fidelity confirmed it would sit on the sidelines, although it said the group had done "valuable" work. – (Copyright The Financial Times Limited 2016)