Former Vice President Joseph R. Biden Jr. raised tens of millions of dollars in the last three months from major donors who gave more than $100,000, relying on some of the Democratic Party’s deepest pockets to sharply shrink President Trump’s financial advantage, according to new federal filings.

Mr. Biden’s biggest benefactors in the second quarter of 2020, when he became the presumptive Democratic presidential nominee, represent a who’s who of billionaires and influencers in Silicon Valley, Hollywood, Wall Street and beyond. Among those who gave at least $500,000 were Laurene Powell Jobs, the philanthropist and widow of Steve Jobs; Meg Whitman, a former Republican candidate for governor of California and now the chief executive of the streaming company Quibi; George Soros, the billionaire progressive financier; Jeffrey Katzenberg, the Hollywood producer; and Dustin Moskovitz, a co-founder of Facebook.

Mr. Biden had previously announced that he narrowly edged Mr. Trump in total fund-raising with their parties in the last full three months, $282 million to $266 million. New Federal Election Commission filings released late Wednesday shed the first light on the biggest contributors powering Mr. Biden’s financial turnaround, from a candidate who struggled to raise money in the primaries to one now outpacing the incumbent president.

Ever since Mr. Biden became the presumptive nominee in early April, the financial floodgates have opened, as major donors who once backed his rivals rallied behind him and small contributors surged toward the chance to oust Mr. Trump. James Murdoch, the son of the media mogul Rupert Murdoch, and his wife, Kathryn, each gave $615,000 in June to Mr. Biden’s shared committee with the Democratic Party. During the primary campaign, Mr. Murdoch had donated to Pete Buttigieg, the former mayor of South Bend, Ind.

Donation limits during the general election skyrocket because, as the expected nominee, Mr. Biden can raise money simultaneously for his own campaign, the Democratic National Committee and state parties. Checks can be as large as $620,600.

Donors who gave at least $100,000 accounted for more than $53 million of Mr. Biden’s total haul in April through June, records show. The Biden and Trump campaigns will not file full reports for their spending and fund-raising until next Monday, though Wednesday’s disclosures offered important revelations both about how much cash Mr. Biden has accumulated and whom he and Mr. Trump have raised money from.

Mr. Biden’s campaign has closely guarded exactly how much cash he has in the bank, along with the D.N.C. But the latest filings suggested he had far surpassed $210 million in cash on hand entering July, a remarkable number given his earlier difficulties.

His two committees that filed on Wednesday showed balances of $92.5 million. Mr. Biden’s main committee and the D.N.C. account had combined for another $118 million, including debts, at the end of May, and spending patterns suggest those balances only rose in June, by far the campaign’s best fund-raising month.

Mr. Trump’s campaign has said he entered July with $295 million in the bank, but his edge over Mr. Biden has eroded from $187 million at the start of April to a fraction of that now.

Mr. Trump has previously leaned heavily on major donors to bankroll his run, tapping many of the mainstays of the Republican money circuit months ago. But in the spring, as the coronavirus pandemic shut down traditional fund-raisers, he relied mostly on online contributions, with $167.6 million of his donations — more than 62 percent — coming via the Republicans’ main online processing site, WinRed, new records show.

Mr. Trump still had some major contributors, raising $27 million via his joint committee with the Republican National Committee that can accept outsize checks. But that was a fraction of the sum that Mr. Biden raised from larger contributors.

Among Mr. Trump’s bigger contributors were Isaac Perlmutter, the former chief executive of Marvel Entertainment, who has been a presence at Mr. Trump’s Mar-a-Lago club, and Bernard Marcus, the billionaire co-founder of Home Depot, who recently dined with Mr. Trump at the White House.

Some super PACs also made financial disclosures on Wednesday.

The Democratic group American Bridge, which has been running anti-Trump ads in some key battleground states, raised more than $15 million, led by top contributors including Phillip T. Ragon ($1.25 million), the founder of a software company; Deborah Simon ($1 million), a shopping mall heiress; S. Daniel Abraham ($1 million), the retired founder of Slim-Fast; Kenneth Duda ($1 million), a software engineer; and Henry and Marsha Laufer ($1.25 million), major party fund-raisers in Florida.

The group also received money via nonprofit groups that do not disclose their donors — so-called dark money — including a portion of a $5.7 million donation from a group called the Sixteen Thirty Fund and millions more from its own affiliated nonprofit.

Stephen F. Mandel Jr., the hedge fund manager who founded Lone Pine Capital, emerged as one of the Democratic Party’s biggest donors in recent months. He contributed $1.5 million to the American Bridge super PAC in May and another $1 million to the Lincoln Project, a Republican-run anti-Trump super PAC, in June.

The Lincoln Project raised nearly $17 million in the second quarter, with donations from some of the Democratic Party’s biggest donors. It has earned a reputation as an irritant to Mr. Trump, running ads during some of the famously voracious television consumer’s favorite shows.

Lincoln Project contributors included David Geffen, the film producer, who gave $100,000; Joshua Bekenstein, a co-chairman of Bain Capital, who contributed $100,000; and Ron Conway, a Silicon Valley venture capitalist, who contributed $50,000 after previously contributing $50,000 in the first three months of the year.