By Fredreka Schouten and Sonam Vashi, CNN

(CNN) -- Political contributions from employees at some of the nation's largest technology companies to Democrat presidential nominee Joe Biden's campaign soared last month -- offering a snapshot of the way in which big tech is increasingly supporting his bid to oust President Donald Trump.

Biden's campaign collected more than $1.5 million last month from employees of Amazon, Google, Facebook and Apple and their technology-focused subsidiaries -- more than triple the roughly $450,000 that flowed from the firm's employees to his main campaign account in July, a CNN analysis of newly filed campaign reports shows.

The sharp increase came as Biden formally accepted his party's nomination during the Democratic National Convention and picked California Sen. Kamala Harris as his vice presidential nominee. Harris, a former San Francisco district attorney and state attorney general, has long-standing ties to some key Silicon Valley executives.

Biden and aligned Democratic party committees raised a record-breaking $364.5 million in August and started September -- and the final sprint to Election Day -- with a $141 million cash advantage over Trump and the Republican Party.

That marked a dramatic reversal in the financial fortunes of Biden who struggled to raise money during the primaries.

In Silicon Valley, the flow of cash to Biden reflects both deep distaste for Trump and his harsh rhetoric about immigrants, along with the tech industry's familiarity with his running mate, said Cooper Teboe, a Democratic strategist who specializes in political fundraising in the tech world.

"The folks here have known and have trusted Sen. Harris for so long that as soon as she was on the ticket, it was kind of 'game on,' " said Teboe, who raises money for a pro-Biden super PAC, Unite the Country, and state Democratic Party committees in Arizona and Wisconsin.

"I've never received more phone calls in my career from people asking about the best places to give than when Sen. Harris was added to the ticket," he said.

Biden has leveled criticism at big tech during the campaign, slamming Facebook for its handling of political misinformation and urging the repeal of a key liability shield for the industry. As California attorney general, Harris pressed tech companies on privacy matters and reached a deal with the industry that allowed consumers to review the privacy policies of apps before they download them.

But she also has deep ties to leading Silicon Valley figures.

Laurene Powell Jobs, a billionaire philanthropist and widow of Apple co-founder Steve Jobs, hosted a Harris fundraiser in 2013. Harris' brother-in-law Tony West is Uber's chief legal counsel. And Facebook COO Sheryl Sandberg hailed Harris' VP nomination last month as "a huge moment for Black women and girls all over the world -- and for all of us."

Powell Jobs also is a Biden campaign donor.

The CNN analysis, based on recent campaign filings with the Federal Election Commission, also highlights the lopsided support for the Democratic ticket among big tech companies. Since January, the Biden campaign has raised at least $3.2 million from donors who work for these firms. Contributions to the Trump campaign, meanwhile, totaled about $106,000.

Patrick Flynn, a Google software engineer, donated $1,000 last month to Biden's campaign, records show. Flynn, who stressed that he's speaking for himself and not his employer, told CNN his donation to Biden was driven more by alarm over Trump's policies than support for Biden's positions.

"There's nothing that I hate about Biden in terms of policy," Flynn said.

"My primary concerns are the dismantling of the institutions of democracy and the rule of law," he said, "the way (Trump) has kind of put people in the Justice Department and the State Department who kowtow to him."

The CNN analysis examined contributions made this year by individuals to the main campaign committees of Biden and Trump and did not include donations to political parties or to the super PACs aligned with the candidates.

Super PACs can accept unlimited amounts from individuals, unions and corporations. The pro-Biden Unite the Country super PAC, for instance, has received big contributions from tech executives. That includes $1.5 million from LinkedIn co-founder Reid Hoffman and another $250,000 from Silicon Valley investor Ronald Conway.

(Hoffman, who has emerged as a major Democratic fundraiser in recent elections, also was among the bundlers who collected money last year for Harris' short-lived presidential campaign.)

"We are proud that our campaign continues to be driven by grassroots supporters from around the country and across industries," Biden campaign spokesman TJ Ducklo said in an email, when asked about big tech's backing.

The President has often railed against social media companies, claiming they are biased against him and conservatives. In an email, Trump campaign spokeswoman Samantha Zager argued that the donations support that claim.

"If anyone is still questioning whether the Silicon Valley Mafia is firmly in Joe Biden's pocket and actively working to stifle President Trump and conservative accounts, this should remove any doubt," she said.

The CNN tally spotlights donations from individual employees of the companies known colloquially as the Big Four: Google, Facebook, Apple and Amazon.

The tally also included donations from those employed by Google parent Alphabet and the major tech-focused subsidiaries of these firms, such as YouTube and Instagram. Those companies are owned by Google and Facebook, respectively.

The analysis did not include employees who listed themselves as employees by the Amazon subsidiary Whole Foods, a business focused on retail groceries. But the tally pulled in donations from other workers in retail positions at these companies, such as those employed at Apple stores or at Amazon fulfillment centers.

About half the money Biden received this year from the Big Four -- $1.6 million -- came from Google employees, the analysis found. At least 44% of the money donated from Google-linked employees came from people who listed their occupations as "software engineers" or "engineers." Amazon and Facebook employees accounted for 19% and 16%, respectively, of dollars given to Biden during the period examined.

Amazon employees led giving to the Trump campaign, contributing roughly $50,000. Amazon employees accounted for about 45% of the dollars donated by employees of the Big Four to Trump, followed by Google at 26%.