The turmoil on Wall Street will affect a wide swath of New York City’s cultural institutions, hurting corporate and individual donations at a time when these organizations are facing what one philanthropist called a “perfect storm” of economic pressures.

“It’s a very challenging time for not-for-profits,” the chief executive officer of CIT and a trustee of the Metropolitan Museum of Art and New York City Ballet, Jeffrey Peek, said. “It’s a little bit of a perfect storm.”

Among the other pressures already facing institutions have been the recent cuts in city funding, diminished earnings on endowments invested in the financial markets, and New Yorkers trying to save money by refraining from buying their usual subscriptions or by buying less expensive tickets.

And now the crises at two financial institutions that have been major supporters of the arts will reverberate across the cultural landscape. Lehman Brothers and Merrill Lynch have donated to many of New York’s major cultural organizations, and Lehman Brothers also has supported smaller organizations that focus on arts education.

A spokesman for Bank of America, which has agreed to buy Merrill Lynch, Ernesto Anguilla, said Bank of America “has a history of honoring commitments that companies we merge with have made.” However, in general, when two firms merge, their cumulative philanthropic impact is diminished.

The effect of the shakeup on Wall Street will be felt not just financially but personally at the Museum of Modern Art, where Kathleen Fuld, the wife of the Lehman Brothers chairman and CEO, Richard Fuld, is a vice chairman. Lehman Brothers has been a corporate member of the museum, and the Fulds have made significant donations of both money and art. MoMA’s spokeswoman, Kim Mitchell, declined to comment on the potential impact of Lehman Brothers’ demise, as did a spokeswoman for the Robin Hood Foundation, where Mr. Fuld sits on the board.

Lehman Brothers and Merrill Lynch each pledged $3 million to Lincoln Center’s redevelopment campaign. A spokeswoman for Lincoln Center, Betsy Vorce, said that both institutions have been making their payments on time, but she did not say how much of their pledged gifts are still outstanding. The president of Lincoln Center, Reynold Levy, said he didn’t know whether any outstanding portion of Lehman Brothers’ commitment would materialize. “I’m guilty of having earned a law degree from Columbia, but I never took a bankruptcy law class,” Mr. Levy said.

Lehman Brothers has extended other significant commitments to cultural organizations around the city. In 2007, Lehman Brothers pledged $1 million, over a period of four years, to support education and outreach programs at the Apollo Theater Foundation. A spokeswoman at the Apollo said she was unable yesterday to find out from colleagues the status of that commitment.

In the past, Lehman Brothers has supported a variety of other organizations, from the School of American Ballet and MCC Theater to arts education programs such as Young Audiences New York and ArtsConnection, which provides arts programs in public schools.

During 2006 and 2007, Lehman Brothers gave $50,000 to the Orchestra of St. Luke’s to sponsor its education programs. The assistant director of development at the Orchestra of St. Luke’s, Rose Bellini, said the organization had put in a request to Lehman about six months ago, asking if the bank would renew its sponsorship, but had received no response yet.

Mr. Levy, who has written a book called “Yours for the Asking: An Indispensable Guide to Fundraising and Management,” said that not-for-profits should be able to weather the economic storm without making drastic cuts, if they have a broad and diverse base of fund raising.

“For those institutions that have approached their fund raising from the point of view of creating a diversified portfolio as to sources and as to methods, they can pretty much withstand the turmoil,” Mr. Levy said.

Still, he said, the loss of thousands of jobs in the financial sector in New York will necessarily put a damper on fund raising, Mr. Levy said. “It’s not so much the institutional giving of Merrill and of Bear Stearns and of Lehman as it is [the donations] of their employees,” he said.