While some dot-com millionaires simply chanced upon their success, the serial accomplishments of Michael Klein showed that the California entrepreneur and financier, who made several fortunes from a handful of deals, was a most talented and astute businessman. Most recently the owner and chief executive of Pacificor, a hedge-fund manager, Klein, who opted for bow-ties over the black polonecks of other internet entrepreneurs, had a Midas touch.

As chief executive of eGroups, the world's most popular group e-mail service, he sold the company to Yahoo! for hundreds of millions of dollars at the height of the dot-com boom, before moving into a career in wealth management.

Michael B. Klein was born in 1970. An exceptionally bright student, he missed out high school and graduated from the University of California in 1988, aged 17. He later earned an MBA at Pepperdine University in Malibu, California, and a law degree at the Santa Barbara College of Law.

On leaving the University of California, Klein founded MIBEK Corporation, a software company that developed financial analysis tools, which was acquired in 1992. He then founded Transoft Networks, a developer of network data storage software, which was bought by Hewlett-Packard in 1999.

That year he was nominated the California State Legislature's Entrepreneur of the Year as well as the Scholarship Foundation of Santa Barbara's Technology & Business Entrepreneur of the Year.

He joined ONElist, an e-mail list management company, in 1999, as president and chief executive. When that company merged later that year with rival eGroups, Klein became chief executive of the new entity. In 2000 he oversaw the sale of the company, for $432 million, to Yahoo!, which later renamed the service Yahoo! Groups. It now has more than 100 million users worldwide.

In 1999 Klein had become the largest investor in the Santa Barbara-based hedge fund company Pacificor, LLC. In 2001 he became chief executive of the company, and in 2002 he bought it out. Pacificor manages assets of about $600 million, catering to institutional investors and high-net-worth individuals with an investment of at least $1 million. As chief executive, Klein was responsible for the strategy of the companies' funds, which were mostly invested in distressed debt — high-yield investments where there is correspondingly high risk that payment will not come good.

In 2000 Klein bought a ranch of more than 1,000 acres in Santa Barbara County, granting a conservation agreement that protected most of the land from development. He also gave $100,000 to the Land Trust for Santa Barbera County for conservation.

In 2002 he bought the Islas Secas, an archipelago of 16 small islands in the Gulf of Chiriqui off Panama's Pacific Coast. In 2004, he opened an eco-resort on Cavada, the largest of the islands, limited to some 20 holidaymakers at a time. It was on this tropical idyll that Klein was last seen alive, last Sunday, when he set off in a Cessna with his teenage daughter, Talia, a friend of hers and the pilot.

The group were heading for the remote Volcán Barú, the tallest mountain in Panama, in what should have been a 45-minute flight to take aerial shots of the dormant volcano 285 miles west of Panama City. On the way to the Álvaro Berroa airstrip nearby, the light aircraft lost radio communication with the ground.

After a 52-hour search hampered by fog and rain, during which Klein's ex-wife, Kim, put up a $25,000 reward for anybody who found the aircraft as well as paying for extra search vehicles, rescuers found the crash site. Klein, his 13-year-old daughter and the pilot were dead but Talia's friend, Francesca Lewis, survived an impact that had reportedly “smashed the aircraft to pieces”. After a three-and-half-hour trek down the side of the mountain she was airlifted to hospital suffering a broken arm and hypothermia.

Michael Klein, internet entrepreneur and financier, was born on December 3, 1970. He died in an air crash on December 23, aged 37