Singapore's largest companies are in the telecommunications, banking, transportation, and manufacturing sectors, many of which started as state-run statutory corporations and have since been publicly listed on the Singapore Exchange. Such companies include Singapore Telecommunications (Singtel), Singapore Technologies Engineering, Keppel Corporation, Oversea-Chinese Banking Corporation (OCBC), Development Bank of Singapore (DBS), and United Overseas Bank (UOB). In 2011, amidst the global financial crisis, OCBC, DBS and UOB were ranked by ''Bloomberg Businessweek'' as the world's 1st, 5th, and 6th strongest banks in the world, respectively. It is home to the headquarters of 3 ''Fortune'' Global 500 companies, the highest in the region.