Many made their money by building their own businesses and are big enough to operate like a pension fund or endowment, with a staff to pick investments. Family offices also typically provide additional services including accounting, estate planning and concierge products.

There’s little data available yet on the investment returns of these collaborative deals by family offices, said Amit, who is chairman of the university’s Wharton Global Family Alliance, which researches family-wealth management. Families usually don’t publicize their stakes or performance.

According to a 2012 Wharton study of about 100 single- family offices, about 16 percent said they had 10-year returns, net of taxes and fees, of more than 10 percent annually. About 18 percent of respondents had returns between 7 percent and 9 percent. Among the group surveyed, 42 percent didn’t answer questions about their performance, the data showed. The Standard & Poor’s 500 Index of stocks gained 2.9 percent annually while the Barclays U.S. Aggregate bond index saw annualized returns of 5.8 percent.

Extra Value

The appeal of investing together or forming a partnership to take a stake is that fees are lower and families can better understand the business they invest in, Casey of the Family Wealth Alliance said. Family offices involved will divide the due diligence by interest and expertise to increase efficiency and maximize their resources.

“Since the financial crisis there’s been a question about whether the value-add from an intermediary fund is worth the cost,” said Ashby Monk, executive director of the Global Projects Center at Stanford University, which studies the movement of financial assets globally. “For these big families there was this perception that they were often getting screwed by Wall Street.”

Kalvoda, whose firm serves as the investment office for a group of related family members, can rattle off the details of the San Diego farming company including how its vertical- greenhouse technology isn’t dependent on soil, how it offers Californians local food they love like cilantro, and how it creates jobs in the community and benefits the environment.

Background Check

For this investment, two family offices analyzed the marketplace and the business model, while a third office determined the fair value of the company. Kalvoda’s firm did a background check on the start-up’s managers even though some of families knew the entrepreneurs personally, she said. Kalvoda declined to name the startup or her co-investors. The families she invests with usually have at least $500 million in assets, she said.

Ward McNally, whose family founded mapmaker Rand McNally, has been advising family offices on joint investments as managing partner of Chicago-based McNally Capital, which serves as a merchant bank to family offices. One of the biggest challenges is reviewing enough deals to find an attractive one, said McNally, whose firm in 2010 helped 12 family offices create an alliance called the Cleantech Syndicate with $1.2 billion to invest in clean-energy companies.