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At the turn of the 20th century, the United States' economy was dominated by an oligarchy of industrialists. More than 100 years after their zenith, their names still resonate: Rockefeller, Carnegie, Astor, Vanderbilt and Morgan among them. These men, known as the "robber barons", amassed wealth and power by monopolising industries. Together they presided over the gilded age of American expansion.

The era was also notoriously corrupt. The barons stopped at nothing as they built their empires. They acquired or crushed competitors, bought politicians and judges, fought unions and exploited workers. Their behaviour created a chasm of inequality across the nation. It took a Republican president, Theodore Roosevelt, to bring them to heel.

America has come full circle since then. Again we have a clique of oligarchs at the apex of the economy. Five tech giants -- Apple, Microsoft, Amazon, Alphabet (Google) and Facebook -- are the most valuable companies in the country. When COVID-19 first emerged in the US in late January 2020, they were worth a combined market capitalisation of US$5.4 trillion (A$7.2 trillion). That was their all-time peak. Since then this sum has exploded a further 60% to US$8.6 trillion. They have had a good pandemic.