It did not move markets, and Berkshire Hathaway shares barely budged, but the marriage of Warren E. Buffett, the Omaha billionaire, to his longtime companion, Astrid Menks, had the financial world all abuzz yesterday.

Mr. Buffett and Ms. Menks formalized a relationship of more than 20 years in a brief civil ceremony at his daughter�s house in Omaha Wednesday afternoon.

The new Mrs. Buffett, 60, has been the constant companion to the 76-year-old financier, even as he remained married to his first wife, Susan T. Buffett, who died in 2004.

The first Mrs. Buffett, who had lived apart from her husband since the late 1970�s, knew and approved of the relationship with Ms. Menks.

�She has been with my father all these years for all the right reasons,� Mr. Buffett�s daughter, Susie Buffett, said in a telephone interview. �I�m so thankful. She loves him and takes care of him. If Warren didn�t have a cent, she�d be with him.�

Investors who thought Berkshire Hathaway shares might have been affected by Mr. Buffett�s domestic bliss saw hardly a blip in the price yesterday � up $296, or 0.3 percent, to close at $96,097.

The marriage is the second time this year that Mr. Buffett has made headlines. In June, he agreed to donate the vast bulk of his $40 billion personal fortune to foundations run by Bill and Melinda Gates, his children and one named for his late wife. Mr. Buffett said when announcing those plans that his health was excellent.

When together and out socially, Mr. Buffett, the older, wise-cracking businessman, seems proud to be with the former Ms. Menks, who is known for putting others at ease.

Mr. Buffett declined to comment, his assistant, Debbie Bosanek, said. Susie Buffett said her new stepmother also preferred not to comment. The wedding was reported yesterday in The Omaha World-Herald.

In many ways, Mr. Buffett has portrayed himself as the business world�s guardian of homespun values � decrying fat paychecks for executives, shunning technology stocks because he didn�t personally understand the businesses, and criticizing tax policies that encourage trading of stocks rather than the patient buy-and-hold approach he favors.

In his personal life, however, Mr. Buffett has been less conventional. His first wife, Susan, left the family home in Omaha in the late 1970�s, after raising the couple�s three children, and moved to San Francisco.

And she introduced a friend, Ms. Menks, to her husband and encouraged Ms. Menks to take care of Mr. Buffett.

The two women had become friends at an Omaha restaurant where Susan Buffett sang and Astrid Menks seated patrons.

�Unconventional is not a bad thing,� Susie Buffett said. �More people should have unconventional marriages.� She said her mother, who was also known as Susie, wanted to be known for who she was, especially as her father�s wealth and fame grew.

�She basically wanted a room of her own. They were very connected in a very deep way,� speaking frequently on the telephone and traveling together, Susie Buffett said. �They didn�t need to be in the same room.�

�Astrid and my mother were very close � really loved each other,� Susie Buffett said.

In an interview with Charlie Rose shortly before her death, the first Mrs. Buffett said of Ms. Menks�s relationship with her husband: �She takes great care of him, and he appreciates it and I appreciate it. She�s a wonderful person.�

Mr. Buffett and his new wife are both known for their frugality. He hunts for bargain stocks and lives simply for a man of his wealth. She often shopped in thrift stores for clothing, assembling fashionable outfits.

�They had a relationship that was so unusual, so fine, and so sophisticated � all three of those people,� said Cedric Hartman, an Omaha furniture maker and friend to the Buffetts for many years.

�We all got to know Astrid about the same time,� Mr. Hartman said. An immigrant from Latvia, �she appeared in town and you couldn�t miss her. She was smart, good-looking and had personal style � she would have been a standout anywhere.�

After she and Mr. Buffett became a couple, friends often received cards signed, �Warren, Susie and Astrid,� according to �Buffett: The Making of an American Capitalist� (Random House, 1995), a biography by Roger Lowenstein.

After his first wife�s death, Mr. Buffett changed his plans for his fortune. Initially, the bulk was to go to the foundation named for his late wife, which supports birth control efforts internationally. But watching the work of the Bill and Melinda Gates Foundation, he became convinced it could make better use of the bulk of his fortune.

He also began to think about marrying Ms. Menks, his daughter said. �He�s been talking about this for a while. It�s something he wanted to do.�

Last Saturday, Mr. Buffett and his daughter went to Borsheim�s Fine Jewelry in Omaha, which is owned by his conglomerate, Berkshire Hathaway, to pick out a ring.

Did Mr. Buffett get the employee discount? �I�m sure he did,� Susie Buffett said.

The bride didn�t see the ring until Wednesday afternoon�s ceremony. �It�s lovely,� Ms. Buffett said. �I think she�s thrilled with it.�

A local judge performed the 15-minute ceremony. The only witness besides Susie Buffett was the bride�s sister; Mr. Buffett�s two sons were out of the country. Afterward, Mr. and Mrs. Buffett, ever thrifty, took them to dinner at Bonefish Grill, a casual seafood restaurant.