America’s 50 biggest donors gave $7.8 billion to charitable causes in 2018, a 50% drop from the previous year. Artificial intelligence and privacy were among their top concerns, according to The Chronicle of Philanthropy.

As usual, tech company executives featured prominently in the magazine's annual ranking. Scroll down to discover who the 10 biggest philanthropists were in 2018.

1.Jeff and MacKenzie Bezos: $2 Billion Inc. (AMZN) founder Jeff and his soon-to-be-ex-wife Mackenzie Bezos made the list for the first time in 2018, knocking Bill Gates off top spot. The richest man in the world and his other half gave about 1.5% of their total net worth to fund non-profit schools and homeless charities through their "Day One Fund."

2.Michael Bloomberg: $767 Million

The former New York mayor and founder of the Bloomberg financial news empire gave up 7.3% of his personal worth to several different causes, including the arts, education, environment, public-health groups and programs aimed at improving city governments worldwide. To date, Bloomberg has donated more than $6.4 billion to nonprofits.

3.Pierre and Pam Omidyar: $392 Million

EBay Inc. (EBAY) founder Omidyar and his wife Pam regularly gift money to charity. In 2018, they gave 3.4% of their net worth to various nonprofits, many of which they founded and help to run. One beneficiary was Luminate, a charity and LLC the couple established in October to support organizations fighting for strong civic participation, data and digital rights, financial transparency, and an independent news media.

4.Stephen Schwarzman: $390 Million

Schwarzman, the co-founder and CEO of private equity giant Blackstone, donated $350 million to a new $1 billion college for the study of artificial intelligence at the Massachusetts Institute of Technology. The billionaire has a net worth of $13.2 billion.

5.Steve and Connie Ballmer: $295 Million

Steve, the former Microsoft Corp. (MSFT) CEO and owner of the Los Angeles Clippers Basketball team, and his wife are big backers of economic mobility programs, mainly in Los Angeles, Southeast Michigan and Washington State. In 2018, they contributed 0.7% of their total net worth to their charitable foundation, the Ballmer Group Donor Advised Fund.

6.Paul Allen: $261.4 Million

Before passing away in October 2018, the Microsoft co-founder continued to be generous. Last year, he gave up 1.3% of his personal worth to a number of causes. They included contributing to the arts and education, studies to improve artificial intelligence problem solving and analysis on how the human immune system works.

7.Mark Zuckerberg and Priscilla Chan: $213.5 Million

Zuckerberg and his wife saw their net worth fall to about $65 billion last year after Facebook Inc. (FB) got embroiled in a data scandal. Nevertheless, they continued to funnel money into the Chan Zuckerberg Initiative Donor Advised Fund last year, which focuses on education, science, criminal justice reform, research, health care and other causes.

8.John and Laura Arnold: $204.3 Million

The retired hedge-fund manager and his wife donated just over 6% of their personal wealth in 2018. Over $129 million went to the Laura and John Arnold Foundation, which is focused on criminal justice, keeping prescription drugs costs down and programs aimed at separating school oversight from campus operations. The other $75.1 million was primarily donated to arts, educational and human-service groups in Houston and elsewhere.

9.Jay Alix: $200 Million

The turnaround expert known for advising corporate giants such as General Motors Co. (GM), Kmart and Enron gave away just shy of 17% of his net worth to the Mayo Clinic. Alix has been donating to the institution since the 1980s, has been a patient there and even said he used its business model for his own company.

10.Edward Bass: $160 Million

The Texas-based venture capitalist and oil tycoon gave up just under 7% of his net worth to help transform Yale’s Peabody Museum of Natural History. Bass, a former Yale student, has been making big-science donations to the college since 1968.