America's billionaires saw their fortunes soar by $434 billion during the U.S. lockdown between mid-March and mid-May, according to a new report. Amazon's Jeff Bezos and Facebook's Mark Zuckerberg had the biggest gains, with Bezos adding $34.6 billion to his wealth and Zuckerberg adding $25 billion. The billionaire gains highlight how the coronavirus pandemic has rewarded the largest and most tech-focused companies, even as the economy and labor force grapples with the worst economic crisis in recent history. According to the report, the net worth of America's billionaires grew 15% during the two-month period, to $3.382 trillion from $2.948 trillion. The biggest gains were at the top of the billionaire pyramid, with the richest five billionaires -- Bezos, Bill Gates, Zuckerberg, Warren Buffett, and Larry Ellison -- seeing combined wealth gains of $76 billion. Elon Musk had among the largest percentage gain of billionaires during the two months, seeing his net worth jump by 48% in the two months to $36 billion. Zuckerberg was close behind, seeing his wealth surge by 46% in the two months, to $80 billion. Bezos' wealth increased by 31% to $147 billion. Because the study timeline captures the stock market bottom and quick rebound, it creates a slightly sunnier picture for billionaires than the full year. For the year, Buffett's wealth has declined by $20 billion, according to the Bloomberg Billionaire's Index, while Gates is down by $4.3 billion. For the year, Jeff Bezos has gained $35.5 billion while Zuckerberg is up by $9 billion.