TL;DR: Covid-19 has decimated many economies and several industries, costing millions of people their jobs. For the world's billionaires, however, the pandemic has helped their fortunes grow, up by more than a quarter to a record high of over $10 trillion.

A study by Swiss bank UBS and accounting firm PwC found that at the start of April, global billionaire wealth stood at $8 trillion. By July, following the height of the coronavirus pandemic, it had reached $10.2 trillion. The previous peak was $8.9 trillion recorded at the end of 2017.

A lot of that increase came from billionaires betting on the recovery of global stock markets when they slumped during the lockdowns (between March and April). With many governments launching stimulus packages, the markets have rebounded, leaving the rich ever richer.

Josef Stadler, the head of UBS' global family office department, said (via The Guardian) that billionaires had "the stomach" to buy more company shares when equity markets around the world crashed. Tech company shares have risen sharply, thanks to increased demand for delivery services, work-from-home products, and video-calling software.

Back in July, Amazon overlord Jeff Bezos saw the largest single-day increase to his net wealth since the Bloomberg Billionaire Index was created eight years ago. As Amazon shares jumped 7.9 percent, Bezos' worth surged by $13 billion to $189.3 billion.

Bezos has seen his fortune increase by $74 billion this year, but that still isn't as much as Elon Musk. The Tesla boss is $76 billion richer since the start of 2020 and is now worth $103 billion.

US senator and former presidential hopeful Bernie Sanders said he plans to introduce a tax on "obscene wealth gains" made by the super-rich during the pandemic. The "Make Billionaires Pay Act" would put a 60 percent tax on the increase in billionaires' net worth from March 18 through to the end of the year. Many of PwC's clients are expecting new wealth taxes and an increase in direct taxation this year as a way of funding government support packages.

A number of billionaires have donated some of their wealth to help those impacted financially by Covid-19. In the US, 98 billionaires donated a total of $4.5 billion, putting the UK to shame—nine of the country's billionaires have donated just $298 million.

The UBS/PwC report covers 2,000 billionaires from 43 markets, accounting for around 98 percent of total billionaire wealth.