(Bloomberg News) Seth Abraham, former president of New York's Madison Square Garden, has used the same barber for 37 years.

"I followed him through five salons," Abraham, 63, says.

Abraham is equally loyal to his money managers, Sam Katzman and Paul Tramontano, who have looked after his assets for more than 15 years. When Katzman and Tramontano left Citigroup Inc.'s Smith Barney brokerage unit -- now Morgan Stanley Smith Barney -- in 2007 to form Constellation Wealth Advisors LLC, Abraham also jumped ship.

Constellation is a family office, a luxe kind of financial adviser first established by the Rockefellers, the Guinness brewing family and other dynasties. Family offices manage money, handle taxes and, in some cases, buy private jets, scout vacation homes, hire butlers and find drug treatment programs for wayward progeny, Bloomberg Markets magazine reports in its September issue.

The latest financial titan to set up a family office is George Soros. In July his hedge fund, Soros Fund Management LLC, told clients it would during the rest of the year return money to all outside investors, amounting to less than $1 billion of its $25.5 billion in assets, and would then operate as a family office. Single family offices are not required to register with the U.S. Securities and Exchange Commission.

These days, you don't have to be a Carnegie or a Soros to have a family office cater to your every whim. If you have as little as $5 million, you can take your pick of hundreds of multifamily firms.

Constellation, with $4 billion under management, is tied with Pitcairn, based in Jenkintown, Pennsylvania, for No. 23 in Bloomberg Markets' first annual ranking of family offices.

HSBC No. 1

The list, which ranks 50 firms by assets, is topped by HSBC Private Wealth Solutions, a unit of London-based HSBC Holdings Plc's private bank. Private Wealth Solutions oversees $102 billion for families in 18 offices around the world.

New York-based Bessemer Trust Co. is No. 2, with $44.5 billion under management.