“A lot of institutions are going to have to scramble,” Tisch said. “We’re all losing money, but the people who have money still have money and they can do something.”

The world’s 500 richest people have lost almost $1 trillion since the beginning of the year, including $331 billion on Thursday, the biggest one-day drop in the eight-year history of the Bloomberg Billionaires Index.

Some of them are writing big checks to fight the outbreak. Bill and Melinda Gates’s foundation said last month it would commit as much as $100 million to the battle against the 2019 novel coronavirus. Half that money will go toward the Covid-19 Therapeutics Accelerator, a $125 million initiative announced Tuesday that’s also funded by $50 million from the U.K.’s Wellcome Trust and $25 million from Mastercard Inc.

In Washington state, another area hit hard by the virus, the Seattle Foundation on Monday launched a Covid-19 response fund with more than $2.5 million from corporate and foundation donors including Alaska Airlines Inc., Amazon.com Inc., Microsoft Corp. and the Starbucks Foundation. On Thursday, the fund had surpassed $9 million, fueled by a $3 million gift from Microsoft billionaire Steve Ballmer and his wife Connie.

‘Natural Inclination’
As global markets crater, nonprofits worry that such generosity could become increasingly rare. Wealthy donors may be more preoccupied with their own balance sheets than the financial health of their favorite charities. Foundations, which are required by law to give away 5% of assets a year, could end up slashing their donations as the value of their investment holdings tumble.

“People are seeing their investment portfolios decline and the natural inclination would be to pull back,”said Alison Powell of the Bridgespan Group, who advises wealthy individuals about philanthropy. “Our advice would be: Double down.”

Meanwhile, organizers are being forced to cancel fundraisers and galas that take months to plan and often generate a substantial portion of a nonprofit’s annual budget. One way donors can help organizations is letting them keep contributions made for galas that are canceled, Powell said.

In New York on Thursday, the Frick Collection’s Young Fellows Ball was nixed hours before it was scheduled to take place. Other prominent events called off include one for the Whitney Museum on April 7, where Laurie Tisch was to be honored, and the Save Venice Ball on April 17, which has been postponed until Oct. 29.

Unique Strains
One concern, borne out by previous crises like hurricanes, is that charities directly responding to coronavirus may get big checks, while other nonprofits are neglected or ignored.

During a crisis, “the entire community is focused on one particular issue,” Gabriel said. “The needs in the community explode and at the same time charitable giving drops precipitously for anything that does not involve that issue.”