Three of the largest donor-advised funds (DAFs) in the nation reported record grant distributions during 2015, totaling more than $5.1 billion.

The largest was Fidelity Charitable, reporting distributions of $3.1 billion, an increase of 19 percent from the previous year’s $2.6 billion. Schwab Charitable reported $1.07 billion in distributions, up 15 percent. The National Christian Foundation (NCF) distributed $966 million, an increase of 4 percent over 2014. Collectively, distributions from the three DAFs was up 15 percent, from about $4.426 billion. In 2014, grants made through all DAFs hit an all-time high of $12.49 billion, accounting for 5.5 percent of all gifts to charities, according to The National Philanthropic Trust‘s 2015 Donor-Advised Fund Report.

DAFs have come under increased scrutiny in recent years, particularly for transparency on payout rates, while they’ve become among the fastest-growing forms of charitable giving. DAFs typically have not reported specific annual payout rates, saying only that they generally distribute at higher rates than private foundations (which are required to pay out at least 5 percent annually). The most recent figures are all based on calendar year 2015 but the DAFs operate on a fiscal year ending in June, when payout rates are calculated.

More than 733,000 grants by Fidelity Charitable went to 106,000 charities last year. It’s an 18 percent increase in the number of grants, with an average grant of $4,200. Fidelity donors recommended 329 grants of $1 million or more, a 27-percent increase over 2014. Since its inception 25 years ago, Fidelity Charitable has made more than $21 billion in grants. Contributions of non-cash assets were up 18 percent. In November, the DAF began accepting contributions of Bitcoin.

Donors used DAFs to respond to urgent needs in 2015, according to Amy Danforth, president of Boston, Mass.-based Fidelity Charitable. Donors recommended nearly 600 grants totaling $3.3 million to support refugee relief. Donors also recommended more than 6,000 grants totaling $8.3 million for relief efforts in Nepal after an earthquake struck in April.

“One of the inherent strengths of donor-advised funds is that they enable sustained giving,” she said. “Donors who contributed to donor-advised funds irrevocably commit those funds to philanthropy. This makes their ability to give – year in and year out – less sensitive to market fluctuation,” Danforth said.

More than 58,000 charities received grants from the San Francisco, Calif.-based Schwab Charitable. Feeding America, Doctors Without Borders, American Red Cross, and The Salvation Army were among those most widely supported.

In a recent survey, more than 65 percent of Schwab Charitable donors said they give more than they otherwise would because they have a donor-advised fund account. Almost two-thirds of contributions to Schwab Charitable accounts in 2015 were appreciated assets, including publicly traded stock and more complex assets, such as restricted stock, privately held shares, initial public offerings (IPOs), real estate, private equity and hedge fund interests.

Grants by NCF went to 20,000 charities in 2015. Donors made contributions The NCF Giving Fund of $1.4 billion last year, up 31 percent over 2014. The Alpharetta, Geo.-based NCF is one of the largest nonprofits offering DAFs focused on Christian donors.