ZURICH (Reuters) -UBS announced changes to its executive board on Wednesday as the Swiss bank presses ahead with its integration of fallen rival Credit Suisse. Switzerland's biggest lender appointed Aleksandar Ivanovic to lead its $1.6 trillion asset management business, replacing Suni Harford who is retiring. Beatriz Martin Jimenez will become the Lead for Sustainability and Impact on the global executive board in addition to her existing responsibilities, UBS added.