(Bloomberg News) John Mack, the former head of Morgan Stanley, is going into business with a 77-year-old tax lawyer who oversees more than $15 billion in investment assets for clients such as ex-basketball star Magic Johnson and the founding family of Estee Lauder Cos., Bloomberg News's Miles Weiss reports.

Joel Ehrenkranz, who co-founded a tax and estate legal practice with his brother Sanford in 1966, joined forces with Mack to start fund-of-funds manager E&M Advisors LLC, according to a registration filing last month with the U.S. Securities and Exchange Commission. E&M expects to raise $500 million this quarter to invest in outside hedge funds and private-equity deals, the firm said in the filing.

Mack, a onetime bond salesman and trader, could help E&M Advisors attract assets from corporate executives and private- banking contacts cultivated during the course of his 35-year career at Morgan Stanley, said Brad Hintz, a bank and brokerage analyst at Sanford C. Bernstein & Co. Since leaving as Morgan Stanley's chairman at the end of last year, Mack has become an adviser to companies including buyout firm KKR & Co., where he signed on in March.

"John's Rolodex would be mammoth," said Hintz, who worked for Morgan Stanley from 1986 to 1996 as a managing director and treasurer. "The classic model of Goldman Sachs and Morgan Stanley was you had the relationship with the company and the executive."

Daniel Schloendorn, a partner at the law firm Willkie Farr & Gallagher LLP who represents Ehrenkranz, said his client declined to comment. Mack said in a brief interview that he had simply lent his name to the venture.

"We have no plans," Mack said. "I've just known Joel for a long time."

After exiting Morgan Stanley last December, the Wall Street veteran set up John Mack Advisors LLC, according to Delaware state records. E&M Advisors was incorporated two months later, with John Mack Advisors and Ehrenkranz's E&E Capital Advisors LLC both holding 50 percent stakes, according to the September filing.

Joel and his brother Sanford, 73, started a tax and estate planning legal practice 46 years ago that catered to high-net- worth individuals, such as the Lauder family, SEC filings show. According to court documents, Joel was an executor for the estate of Alan Tishman, the real estate developer who "helped transform New York's skyline," according to the New York Times.

The law firm began managing money for its clients, initially by having them invest in commercial real estate partnerships and then in hedge funds, said a person familiar with the firm who requested anonymity because of confidentiality agreements. In a 2004 civil trial tied to his former role as the president of Walt Disney Co., Michael Ovitz testified that Joel Ehrenkranz was one of his two principal money managers and had also been one of his main tax advisers from 1990 to 1995, according to court transcripts.